In the revised and updated edition of "Ainslie's Complete Guide to Thoroughbred Racing," published in 1979 by Simon and Schuster, author Tom Ainslie notes, "It is entirely possible to stay even with the game by playing no claimer that has not had a race within a week—provided one is prepared to apply other simple handicapping rules with equal inflexibility and is willing to pass up a considerable number of races."
A couple of paragraphs later, Ainslie adds: "Allowance, handicap and stakes horses need not race so often to maintain their sharpness."
Does Ainslie's betting advice still hold true? Thoroughbred racing has changed a lot since 1979. Horses don't race as often as they once did. According to the 2026 Fact Book on The Jockey Club's website, the average number of starts per runner was 9.21 in 1980. In 2025, the number was 5.79. Is a busy racing schedule still a good sign for claiming horses? And do elite horses perform as well or better with more time between races?
Using Race Lens from Equibase, we analyzed data from thousands of races to determine the answers. We crafted custom handicapping angles and back-tested them over the past year of results to determine how much time between starts is ideal in various types of races.
Note: Data research was conducted over several days. As such, the exact races contained within the one-year sample may vary slightly from one category to the next.
Overall trends in all races
We'll begin with a broad review of all races in the Race Lens database from the past year, analyzing the performances of horses who last raced 1-7 days ago, 8-30 days ago, 31-60 days ago, 61-180 days ago, and 181+ days ago:
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 7,822 | 11,074 | 12% | 12% | 12% | -32% |
| 61-180 days | 14,196 | 22,907 | 13% | 13% | 13% | -27% |
| 31-60 days | 24,556 | 58,718 | 14% | 14% | 14% | -25% |
| 8-30 days | 31,079 | 130,523 | 14% | 14% | 14% | -26% |
| 1-7 days | 2,546 | 3,355 | 16% | 16% | 16% | -22% |
A subtle, but meaningful trend is evident. Horses with less time between races compile higher win percentages than those entering off long layoffs. In addition, horses returning from layoffs of 181 days or more generate the poorest return on investment (-32%), while horses running back in 1-7 days are the best betting proposition (-22% ROI).
Claiming races
The overall trends are even stronger when reviewing the data for claiming races:
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 2,647 | 3,577 | 11% | 11% | 12% | -34% |
| 61-180 days | 5,258 | 8,315 | 13% | 12% | 13% | -24% |
| 31-60 days | 9,603 | 21,271 | 15% | 13% | 14% | -24% |
| 8-30 days | 12,969 | 60,488 | 14% | 15% | 14% | -26% |
| 1-7 days | 1,430 | 1,884 | 16% | 16% | 15% | -20% |
Horses returning from layoffs of 181 days or more in claiming races should be avoided. The win percentage is low (11%), and the ROI is a poor -34%.
The highest win percentage (16%) and best ROI (-20%) can be gleaned by betting horses running back in 1-7 days. Perhaps by applying "other simple handicapping rules with equal inflexibility," Ainslie's strategy of betting claimers who raced within the last week can still be a break-even betting proposition.
Graded Stakes
Running the same data analysis for graded stakes horses reveals very different results:
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 106 | 130 | 15% | 15% | 12% | 15% |
| 61-180 days | 286 | 552 | 15% | 13% | 14% | -18% |
| 31-60 days | 457 | 1,785 | 14% | 13% | 13% | -23% |
| 8-30 days | 404 | 1,245 | 10% | 12% | 13% | -38% |
| 1-7 days | 7 | 8 | 13% | 25% | 0% | 20% |
Over the last year, betting every horse who entered a graded stakes off a layoff of 181 days or more has been a profitable strategy (+15% ROI), though the small sample (130 starters) includes a 68-1 longshot winner.
For graded stakes horses, win rates and ROIs generally drop as time between races decreases. Graded stakes horses running back on 8-30 days of rest compile a low 10% win rate and a poor -38% ROI.
Only once you reach the category of 1-7 days between starts do the trends reverse, with a 13% win rate and a profitable +20% ROI. But the sample size (eight starters in seven races) is extremely small.
Ainslie was right—quality horses needn't race as often as claimers. In fact, the data suggests they benefit from more time between starts.
Sprints vs. routes
Does the ideal amount of time between races vary depending on whether a horse is running in a sprint or a route race? It makes logical sense that horses returning from long layoffs are more likely to prevail in a sprint than a route, but is this actually true? Let's find out:
Sprints
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 5,848 | 8,539 | 12% | 12% | 12% | -34% |
| 61-180 days | 9,362 | 15,183 | 13% | 13% | 13% | -25% |
| 31-60 days | 15,640 | 35,163 | 14% | 14% | 14% | -27% |
| 8-30 days | 20,309 | 83,248 | 14% | 15% | 15% | -26% |
| 1-7 days | 1,754 | 2,348 | 15% | 16% | 16% | -29% |
Routes
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 1,970 | 2,539 | 12% | 11% | 12% | -27% |
| 61-180 days | 4,827 | 7,715 | 13% | 13% | 12% | -29% |
| 31-60 days | 8,916 | 23,555 | 14% | 13% | 13% | -22% |
| 8-30 days | 10,763 | 47,244 | 13% | 14% | 14% | -26% |
| 1-7 days | 792 | 1,007 | 16% | 15% | 15% | -6% |
Less time between races is beneficial in both sprints and routes, and you can achieve a nearly break-even -6% ROI betting all horses running back in 1-7 days in route races. But overall, there isn't much difference between sprints and routes. Returning from a layoff of 181+ days in a route doesn't appear to be harder than doing so in a sprint.
Dirt vs. turf vs. All-Weather
Do racing surfaces affect the ideal amount of time between races? We've crunched the numbers for dirt, turf, and all-weather tracks, revealing interesting results:
Dirt
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 6,133 | 8,637 | 12% | 12% | 12% | -35% |
| 61-180 days | 11,398 | 18,013 | 14% | 13% | 13% | -24% |
| 31-60 days | 20,083 | 45,459 | 15% | 14% | 14% | -25% |
| 8-30 days | 26,248 | 109,946 | 14% | 15% | 15% | -26% |
| 1-7 days | 2,273 | 3,038 | 16% | 16% | 16% | -21% |
Turf
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 1,657 | 2,389 | 13% | 11% | 11% | -23% |
| 61-180 days | 2,757 | 4,804 | 11% | 12% | 11% | -36% |
| 31-60 days | 4,428 | 13,155 | 13% | 12% | 12% | -24% |
| 8-30 days | 4,788 | 20,427 | 12% | 12% | 12% | -26% |
| 1-7 days | 272 | 317 | 11% | 14% | 12% | -27% |
All-Weather
| Total Races | Total Starts | Win % | Place % | Show % | ROI | |
| 181+ days | 734 | 1,009 | 14% | 11% | 14% | -18% |
| 61-180 days | 1,331 | 2,418 | 12% | 12% | 11% | -14% |
| 31-60 days | 2,181 | 5,417 | 14% | 13% | 13% | -19% |
| 8-30 days | 2,718 | 11,792 | 13% | 14% | 14% | -26% |
| 1-7 days | 180 | 206 | 13% | 14% | 16% | -4% |
Dirt horses benefit from less time between races. The highest win rate (16%) and best ROI (-21%) can be found betting horses running on 1-7 days of rest.
On turf, there isn't a category of time between starts that stands out as especially better or worse than others. For the most part, they generate similar win rates and ROIs.
If you're going to bet a horse returning from a layoff of 181 days or more, it helps if they're running over an all-weather track, where their win rate is 14%—slightly higher than on dirt (12%) and turf (13%). The ROI (-18%) is also better.
The -4% ROI generated by all-weather horses running back on 1-7 days of rest is eye-catching, but it's bolstered by a 58-1 winner amid a relatively small sample size (only 206 starts).
Takeaways
As a broad rule, the less time between races, the better. Horseplayers generally find superior ROIs and higher win percentages betting horses running back on short rest than those returning from long layoffs. This is especially true in claiming races and on dirt. In these types of races, it's better to bet a horse running on 1-7 days of rest than one returning from a layoff of 181 days or more.
However, when it comes to graded stakes horses, the opposite is true. Bettors encounter the highest win rates and best returns backing horses returning from long layoffs. The less time between races, the less appealing the betting proposition—at least until you reach the range of 1-7 days, at which point the sample size is too small to trust.
Even today, there are still nuggets of truth in Ainslie's wisdom about time between races. Bet claimers running on short rest, and don't worry about graded stakes horses taking plenty of time between races.
Special thanks to Equibase, which provided me with a free subscription to Race Lens in exchange for product promotion. All opinions remain my own.
