i havent done 3d comms but ive done 2d animation comms which have a similar problem to 3d where the prosuct graduates through various steps and fixing simething in a previous step is more work than it seems.
>>1010260 has a point that a 3d model can be prepared in such a way that revisions are easier, but a consumer client is not the same as a studio head.
my strategy is to work woth them at every step and get their confirmation everything at that step looks good to them.
I'll sketch the main scene and get them to say they like the designs. then i show them an animatic to get them to confirm toming and movement. then the sketch frames. then the finished frames.
if you've got a really frustrating client who keeps wanting a little more, a little more, that's too much kinda thing then you need to keep your eye on the prize. youre running a business, this client isnt just their fee, theyre also a marketing node. how well you accomodate them will color what they tell others about you. some nitpicky clients know theyre nitpicking and if you can muscle theough it will be extra appreciative.
a good coping strategy is to find people you can talk to, in real life not electronically, and talk major major shit.