I remember a time when the fillet tool was extremely fastidious. Then it was reworked and now it will fillet almost anything, which is great.
I wish the same thing could happen to the shell tool. It doesn't work well with subdivisions at all, and for complex objects it will often only shell by a small amount.
When VW choose to rework it, as I hope they will, I could also use a 'Center' option besides 'Inside' and 'Outside'.