Yeah, painting weights is a headache! It takes a lot of practice. As you know when you add or replace weights on a joint, the adjacent joint receives or gets that weight info. This gets a bit tedious. One helpful tip is to "toggle hold weight on selected" on the joints to keep the weight info. Nothing will be added or taken away.

Also remember to prune small weights under Bind>edit smooth skin>prune small weights, set prune below at 0.0500 (this influences the small amount of weight to be taken out, experiment with this). This way, small influenced weights on the joints will be taken out which make your job a bit easier.

Use the component editor for small details or miniscule deformations. I usually do this as the last step.

I'm sure you know about mirror weights. Which cuts your job in half.

Pretty much, there are no tricks for painting weights. It's just tedious work. As time goes by you just get faster. Keep at it.