This is the second time, or third, I bring this up, surprised that I don't get everybody's support. So here is what I suggest:
This is really the worst part of Revit in my opinion since it defies the real wander of skipping the tedious art of editing and double checking where the computer could do better than us humans.
There are too few grades of strength to wall and floor layers so the joins never work properly. There should be more grades to allow for automatic joining as required. The joins should be automatic! No join function needed. The editing tool does not work properly. Very unstable. In most cases the editing is not saved. But who wants it anyway. we need better control over wall joins in general and prefer that it will happen by itself.