When I finish developing film there is, naturally, a little water left in the film spools. I can shake out most of it but if there is a little left inside and I put in more film, can it ruin development or cause streaks?
No it will not. But depending on your material of the reel (plastic ??) then it's impossible to load another film on your reel. You will simple not be able to load it when it's not completely dry.
You can reload stainless steel reels without waiting for them to be completely dry, but I wipe them off with a dry paper towel so there aren't any large drops on them. If you use a presoak, even large drops of water on the film shouldn't matter. If you don't use a presoak, water spots might cause uneveness.
Thank you for the advice. I'll just get a spare reel because I don't think I could trust myself to put anything meltable in the oven. I'm notoriously forgetful . . . . .