Some of the top trainers, set their horse to peak at group races, use this pattern. Their preceding start, used it to toughen up the horse, and then given 21 days or 7 days, to peak the horse. For horses that can win first up in past preps, but ran poorly in the first few starts this prep, signs are that the trainer held up the horse for a target race/distance, espeacially if its back up in 7 days, as these 1st upper winners only need 1 week of work to send them to peak form.
It always paid to check carefully of horses that step up in distance by more than 400m in 7 or 21 days break.
For sprint races, some trainers use 1600m as a toughen up race, and then drop back to sprint distances, where it may peak on the day.
Such pattern does not mean it will win but just an indication of the trainer targetting the specific race / distance.