When I have used my rubbers 50 times what comes down to approx. 100 hours I change them. Is this to soon/to late?
I use a tensor on BH and Chinese on FH. Do you have some kind of usage standard?
I hit about 10hrs/week with intensity, and a couple of hours to boot in a more leisurely fashion. After play I clean my rubbers, and store away my blade in a closed case, in-house where it's not to cold (or hot) and not too dry or humid.
With ESN rubbers I usually notice a bit of degradation in a month or so, a little more after three months. My Butterfly rubbers about the same. Some, but not all of them, start to "slip" at some point. It's usually not just the rubber losing its grip, but also the humidity. Rasant Grip had that, but Tenergy 05 and Rozena also tend to get more sensitive to humidity after a while. I usually notice during play and adapt my game a bit, moving away from deeply spin-based to a flatter, more direct style. There are limits to that.
I try to play with a single set of rubbers per season/competition. That usually boils down to three changes a year, with summer and winter sometimes offering intervals fit for experimentation -- adapting stroke techniques, footwork, but sometimes also trying out other equipment out of curiosity. Others hold on longer to their rubbers, some to the extent that I find them unplayable, but there are also scores of players that change rubbers that to me feel barely broken in. To each her own.