Thanks for all the feedback! I really do appreciate it. Here's my use case:
1. Why a separate file: My main project has several dozen tracks, effects, markers and tempo changes and stuff like that. My vocals will be a group of 4-5 women and another group of 4-5 men. They will all actually be me and my wife, recording clones of ourselves with multiple takes. Also, my wife has a really great voice but is totally untrained, so I took her part and broke it up into short, singable snippets that she can securely handle, then I will splice them together to make the real part. 4-5 times, to make the group of women. Also, to add both a layer of crispness and a layer of strangeness, I record at half tempo, then use the length tool to shorten them. Lastly, because this song takes place on an alien planet, I am having her sing a 2nd or 3rd up, then transpose her down to get a sort of alien effect. So, combining the splicing of clips, the multiple takes, the length tool, the transpose tool, a little Melodyne, and doing it all 4-5 times, it's way easier to have a "sketchpad" that isn't cluttered with everything else in the project. I could add tracks at the bottom and go way out past the end of the piece to keep it all separate, but this seemed a saner choice.
2. How I use take lanes: I think Take Lanes were designed for people doing a bunch of takes of a part, then saving one and moving on. Problem is I am actually saving more than one of the takes, as I am recording clones of myself, either in unison or harmony. Sometimes this is simple double-tracking, but just as often I'm recording a group of 4-6 voices in unison. My preferred recording method is to do takes of small phrases and then splice them together, rather than sing a whole song in one take. A single verse might be split into as many as 4-6 separate phrases, each one recorded separately. I find that by singing the same phrase over and over I learn quickly what vocal inflections I like or don't, what notes I'm having trouble hitting, etc.
Also, due to limited quiet time in the house, I have to record all my phrases in one session, so I'll end up with a track of dozens of phrases, and maybe a dozen takes of each phrase. My vocal recording tracks get enormous, with a lot of vertical scrolling involved.
So, imagine this track with dozens of small clips, and now I have to shorten the length, transpose them, pitch-correct them, and finally copy them to the real project.
Ideas welcome!