My old club - Pre-season nets where 5-7 attend. Fast bowlers try to knock your head off, other 'bowlers' aren't regular so generally struggle to hit the green bit. I didn't bother after my 3rd season, I worked with a coach then did 1-to-1 sessions with one of our actual bowlers who wanted to work on his line and length. Last season we tried to do an outside fielding session a few times but it descended into a mess about with everyone trying to alter drills.
During the season we didn't do nets except once or twice after a very bad performance. One session would definitely fix all the problems.
My new club seem to be the opposite. I know when nets are already and I expect them to be well run and constructive. It is certainly one of my main reasons for moving clubs. I find it very difficult to improve as a keeper just on my own with a bowling machine, it is good for some stuff but I can't practice run outs, diving catches etc.