Like @newmarket I tend to carry on doing what I'm doing until the first few regular frosts or even into December. I would say 'first frost', but we had one a couple of weeks ago and then a few days and nights of almost constant temperature with rain.
In fact with the rain, I think the fish carried on munching big time.
Tim makes some other very valid points, stock levels, bait reliant, how busy a venue, etc.
My syndicate is quiet anyway, the most I've seen is 9 or 10 on 45 acres, yet compare that to a commercial and you would have 50 anglers on that lake...
The commercial is 'overstocked' so you catch compared to the syndicate.
I do use less bait, but I tend to up the numbers of boilies and drop the levels of particles. Particles I think rely on the oils within to attract, in cooler weather the oils cloud up and solidify being less attractive.