Does practicing on a tight table help or hurt?
It depends.
It depends on how you react and what you do about the bobbles. If you do nothing, it hurts. If you stop and figure out why it bobbled, it helps.
Lately I've been playing on some very tight, finicky Diamonds. At first it was aggravating beyond words - hitting a shot just a hair to the outside facing or barely brushing a rail and having the ball hang up. It's a pisser. But what I did was to start to look at all that as indicators of an imperfect setup and stroke and, lately, after much introspection, angst, and work, I have had success.
Personally, I think a table can be too tight for pool to the point that the whole thing becomes something other than pool. You need to be able to work the ball and that means a little leeway at the pocket. But there's never anything wrong with being able to be laser accurate. And when you get a hold of that... it is amazing how much you can still work the cue ball.
Lou Figueroa
Most 14.1 players dont like diamond tables for that very reason. Yep, a diamond will turn a 100+ ball runner thats use to a GC into a 50 to 60 ball runner unless they do as you suggest.
Most give up and just complain instead of adapting.