I don't think there's any secret to learning them quickly, except that as you say, they can be somewhat repetitive. Just don't practice the repeated parts? I would also say that the more of them you learn, the faster it is to learn new ones. I played Op 15. in a recital about a month ago and I think it was about a week or two each to get them under my fingers? Probably a couple months before I thought they sounded good? Maybe another year before I'm really truly happy with them?