It is an irksome habit, and I wish I could break it and plough on regardless. But I always find when writing anything lengthy that there comes a point by which I’ve accumulated enough little niggling worries about things I’ve already said that I just have to go back to page one and work through again from the beginning, ironing things out. So that’s what I’m doing at the moment with my category theory notes. The exercise is — surprise, surprise! — taking longer than expected, but I hope has made for some interesting expository changes, about which more in due course, when the revised/expanded notes are ready for prime time.
Meanwhile, here’s an update/expansion of the page on Category Theory giving links to (broadly speaking) student-orientated materials available online.