Previous success (or promise for that matter) over a similar distance or going or on the same racecourse is considered such a critical indicator that most racecards list this information as a key attribute of the form.
Unfortunately not. While a horse obviously has a preferred distance, in the same way that a human athlete wouldn’t compete at 100m, 5,000m and marathon (David Weir excepted!), the data shows that bets on previous distance winners are only marginally more successful (2-4% better win rate). Worse still the bookies have already factored these characteristics into the odds so there is a negligible profitability benefit in using this betting strategy.