I've just grabbed a random, heavily OO module from my own code library. It has 60 instances of "self", or 240 characters, out of 18,839 characters in total (including newlines). Removing self will decrease the number of my keystrokes and the amount of pure typing time (excluding thinking time, debugging time) by about 1.2%. I don't call that "a lot" -- it's actually quite small. And it becomes vanishingly trivial when you factor in that most of the time spent programming is not typing but thinking, testing, debugging, etc.
Well, maybe I don't program in Python the "right way" ;-), because it's a bit more in my code. I repeated this test, and for a random module holding some GUI stuff (built using PyQt) and it's more than 5% (213 selfs out of 16204 characters). With a small app for creating dungeon tiles for role playing games I astonishingly got same very similar value (484 * 4 / 35000) ;-) Maybe it's a feature of programming with a lot of gui stuff, which I do. But 1 of the 20 chars used for a self is quite a lot for me.