I visited the Hermitage late September hoping and believing that there would be less crowds. Maybe it was less than the summer but it was still overwhelming and chaotic.
I was on a cruise and had originally signed up for the 3 hours at The Hermitage in the evening shore excursion but changed to 5 hours at The Hermitage with The Gold Room which was done in the afternoon.
I regret the change. I found the crowds overwhelming and chaotic. My tour was walking too fast for me, almost running, and I fell down at one point.
If I were to do it over, i would have stuck with the evening shore excursion.
Also, I caution about the cloakroom. If you bring large bags or wear a coat, you will have to store such items in free lockers in the cloakroom. There is little problem when you hand over your items but collecting them later was quite a problem. We were leaving about 5 pm with thousands of other visitors and it was chaos that was almost frightening. Try to avoid the cloakroom which I know is not always possible.
P.S. The Hermitage is amazing but there was a lot of rushed and very fast walking through. it was often impossible to enjoy and or take pictures.