I don't think the number of AIs actually matters. If multiple AI's can do a job, then a single AI should be able to simulate them as though it was multiple AI's (or better yet just figure out how to do it on it's own) and then do it as well. Another thing to note is that if the AI makes a copy of its program and puts it in external storage, it doesn't add any extra complexity to itself. It can then run it's optimization process on it, although I do agree that it would be more practical if it only improved parts of itself at a time.