I guess I'm the odd ball here. I'll preface what I'm about to say by saying I vape pretty much exclusively in TC. I just vape my tank until I notice the vapor is really thinning out (empty). Then I put in the new juice. I usually find after a few or ten (lol) puffs, the new flavor is coming through. I just switched from Lemon Meringue to Vanilla Custard and it took maybe at most a quarter tank before the Lemon was gone. If I feel really adventurous I rinse the tank and drip tip, but don't mess with my coils unless I'm going to rebuild them. I smoked for quite a few years so maybe I'm not as sensitive as some (haven't smoked for going on 4 years though). If I liked the flavors in the first place, I don't mind getting a mix for a little bit of the tank. I guess I really am the odd ball lol.
Cheers,
Steve