Don,

You're absolutely right about repetition. The more you rehearse a song, the more natural it becomes. I have old Irish stuff I do that is 100% muscle memory. I will panic a bit before a verse but then the mouth opens up and the words fall out. Your brain has excellent filing capabilities if you let it. When trying to learn difficult lyrics I resort to writing them out long-hand a few times. It makes the pick up a lot quicker for me as opposed to listening or reading the words.

I don't object to folks using a book,I've done it myself, but I think the perfomance is enhanced without it.

Lefty