I received an interesting email from an astute follower. Here is an extract

"The times weren't a result of some change to the track profile or maintenance. In the main the quality of fields over that time hadn't altered greatly, in some cases I was seeing the same horse trained by the same trainers?

Eventually I concluded it was a result of the mindset of the younger drivers. You will be familiar with the older trainer/drivers who knew almost to the second a horse's ability and would drive to (i) save their horse for next week and (ii) to ensure it picked up a place check, where possible.

Well the younger drivers don't have the weekday attachment to their horse. They jump into the sulky, drive the horse in most instances making greater use of the horse and after the race hand the reins back to the trainer."

It is no doubt a factor - one that I had never thought of