I frequently forget to shoot a clean plate of a shot where I need to do a ton of rig removals, and end up having to make a clean plate from bits and pieces of the actual animation.

On that same note there are often shots where I should shoot with double exposures one with and one without the character and rig to really make the removal quicker and easier and I just don't, I figure one frame at the end will do the trick and part way through I realize I might need to pull focus or something and just one clean plate won't cut it for rig removal.