The great thing about shooting classifier matches, in both IDPA and USPSA/IPSC is, if you pay attention as you go along, you can learn what particular skills you need more practice on!
I will go out of my way to shoot classifier matches in either discipline. Regular club matches are not as much of a priority.
I usually do really well on Stage I & II and then sometimes "crash & burn" on Stage III. I have identified my problems there as (1.) shooting too fast and (2.) crowding cover, particularly when shooting from behind that barrel at the 15 yard line. Getting too close to your cover means that you have to contort to engage some of the targets, and having an unstable shooting platform leads to lots of misses . . .
I'm not particularly fast in any event, but if I'm on my game, I'm smooth and accurate.