I'm just curious how many of you play casual matches or other events on the same days as your regular USTA league play? It seems like my opportunities to play come in bunches and since I like to play so much I just can't say no. For example, on Sunday I am playing from 7am-9am in casual doubles that is fairly competitive and fast paced. Then, I have to travel two hours to play in a USTA doubles match at 1pm. After that, I have to travel two hours back to the club and play in regular "club men's league" doubles from 5:30-7. I am in good shape and it doesn't bother me to play that much, but I am sure I am at a disadvantage for the last sets of the day. If the USTA match was the last of the day, I would probably rethink my schedule.
With me, my game stays fairly consistent but my serve tends to wane when I get tired mainly because of lack of concentration from too much playing and repetition.