I think I've figured out why sometimes I have such a hard time knitting for others. Its only really one big reason.
Fitting. I can measure what I'm making all I want against my own arm/head/foot/etc. but it does no good when I'm not exactly sure how much bigger to make it for whoever I'm making it for. If I'm making it for me, I don't mind taking forever to keep redoing it until it fits. But if its someone else, how am I supposed to know when its just right for them? I have no way of knowing. All I can do is guess and hope I'm right.
It's starting to be the time of year when everyone starts thinking presents. I'm making mine this year and probably every year after this. But I always fear that what I make won't fit.