Asking for Recommendation Letters

This topic has been asked countless times I’m sure but I can’t find solid answers to my questions.

I need reference letters from professors for multiple internships. Should I ask them to write multiple specific letters? Write one general letter? If I apply to many internships I can’t expect them to write many letters.
Should they send these letters out? Should I keep these letters on file (but not read myself of course) so I can send them out should I find other internships?

Thanks!

In my experience, professors generally send the letters directly to the program, unless the program specifically specifies that the applicant should submit the letter. Professors are used to writing and submitting rec letters for students for multiple programs, and they usually write one main letter and then tweak it to fit the different programs. The professors who wrote my letters of rec also kept them on file for a while and said to let them know if I needed the letter for another program in the future since it was fairly simple to adapt the letter to a different program.

What I did when I asked for the letters was compile a list of the programs I was applying to, the deadlines, and how the program wanted the reference letter to be submitted (and if the program wanted a hardcopy mailed, then I would give them an addressed and stamped envelope). If the program wants you (the applicant) to submit it directly, you can always have the professor send it to you. But if the program wants (or provides the option for) the professor to submit the letter, then they should be able to do so as long as you let them know how. I’ve never had a professor say they had a limit on the number of letters they are willing to write since it’s essentially the same (or a very similar) letter every time.