Well it basically comes down to trial and error and gaining experience from it all, if you ask me. And with every situation it will vary and also it will depend on how of a protagonist the piece is. So if it’s on a spot that is going to be very noticeable, you may want to go with a high count like a cylinder with 8 vertices to get a sturdier shape, but then you have to take into account that all those loops will be going al lover the model, so you’ll have to simplify things with loops that turn from 8 to 4 or 4 to 2 or maybe you can afford your model to be very high poly so it wont matter.
Each shape will require an amount of vertices that if you fall short, you’ll be in trouble, if you use too much, it’ll be a nightmare to control. So that sweet spot comes with experience and making lots of mistakes and starting over when the mesh is giving you too much trouble. I guess that is one of the main points, if you see you used too much or too little and you’re wasting to much time trying to fix things… just start over from scratch. You will gain experience points in your brain and you’ll gain speed and now you know how to start and adjust from there and that’s how you build the Spidey sense of how much geometry something will take.
