I want to apply to quite a few REUs and I'm asking a professor to write me recommendations. I was wondering whether for most REUs, he could write one recommendation and then use it for everything, or whether he would have to rewrite or edit the letter for each program. This is so that I don't feel bad "spamming" him with requests from various programs.
Also is it a faux pas to put down the professor's email into the request box in the app without sending them an email? (Even though I discussed this briefly some time ago with professor)