Problems are visible in blender 2.8 to 2.9 versions including LTS
When it happens:
for most of the models we rig, symmetry is one of the important things when we weight paint. for that we have x-mirror at the options menu and symmetry axis. they have their own advantages, but if you are not used to this workflow, in my opinion it is very confusing. I’m guessing even sometimes Blender doesn’t understands you and tries the “topological mirroring” even it isn’t enabled… that happens when your model is offset from axis like 5 microns (ctrl+a applied)
· just when entering weight paint mode, Blender checks symmetry. if the mesh is asymmetric, blender leaves a warning message.
· when painting accidentally or by purpose without symmetry, blender leaves a warning message.
basically I’m thinking blender has to give you feedback that how it has to be.
Undoing just after you change brush settings, or enabled symmetry. brush settings you did is gone.
When it happens:
you change the brush settings, or enabled symmetry, then you paint some area but you didn’t like the result/ changed your mind, you undo. and suddenly you realise that to make the paint again you have to do the brush setttings again.
·Blender undo system in this case isn’t seperate somehow: it is undoing both the weight paint (also texture paint) and the brush settings at the same time. if we can seperate those two actions the problem is gone.
Painting hard to reach areas, overlapping (like t-shirt on the skin) areas, seperate mesh areas.
· fill option: we have face selections and vertex selections. to cut worktime instead of going to vertex groups doing something like selecting verts and just pressing key F could be really useful. there are options similar to this idea but not quick enough.
· sometimes Alt+B command is not useful when I want to paint a “section” of mesh. a little upgraded “sectioning of mesh” feature in addition to fill option I mentioned is really useful for overlapping areas.
Automatic Weighting tweaking.
you have to clean automatic weighting especially large areas shared to many bones. this is actually normal. but to save time things can be made.
· a slider to adjust spreadiness ratio of 3D area of all bones
· Blender checks the last characters of the bone names. If Bones has text “.L”/".R" (for left and right)
blender gives more priority (means more weight area) to the spine bones for example.