Human memory doesn't work like your hard drive. The notion that you have some sort of 'free disk space', because you don't remember function names is ludicrous. Quite contrary, the more you train your memory, the more you can remember.
I didn't say it works like a hard drive. Yeah, the more I train, the more I remember what I trained and remembering function names and argument order is something I specifically don't want to do because I can only train my memory for so long each day and I'd rather remember important things, not trivial shit like that.