Monday: Lady borrows twenty bucks from me and promises to pay back on Friday.
Friday: She's all excuses and asks for more time.
Sunday: She pleads and asks to borrow fifty more. I lend it to her.
Following Tuesday: She pays back a hundred bucks, I pocket the extra thirty.
This is her regular pattern. As long as she continues cranking out interest like that, it's no bother that she misses deadlines.