Interesting. I don't even have enough projects to warrant a master list yet. I feel the same, way, though, that my work might suffer if I split my focus. Still, even when I completed the first draft of my current manuscript, I didn't think: "oh maybe I'll go work on something else for awhile" I sort of caught my breath and thought: "Phew!! That was hard, and it looks like it's getting harder from here." I waited about a month before going back to it, but there was no doubt in my mind that that was where my focus needed to be exclusively.
Oh, I don't have loads of projects on the list. Mainly it's just an organized dumping ground for my ideas where I can put down details as they occur to me, and then as I start working on them the entry slowly morphs into an in-progress meter, then a record of the project existing between edits! I started it with only one project when I had an idea for my second. It's never too early to start organizing.
And I, too, like to work on something else while I let a draft sit before editing. Typically I outline and research my next project for a week or two before I edit the one I just finished. That way I don't get too bogged down in the writing of the next project but still get something done, and let ideas/theories cement in my mind. For me, staying on task is all about staying organized and keeping everything within the lines, if you follow my drift.
Sometimes I feel like I take too long. I like to contemplate every blade of grass, when most people aren't going to look that closely. I'm all for quality, particularly when it comes to genre fiction, but sometimes I wish it didn't mean that I move as slowly as I do, pouring over my world. I'm the same way when I paint actually -- super technical. Every shade must be accounted for. I can drive myself a little crazy.
But I guess if that's what does it for me, I shouldn't deny myself. Still... one of these days I'm determined to write something that isn't super detailed, or ridiculously epic, or full of intensive worldbuilding.
I'm like this too--I love my details, and I don't generally work on things that require worldbuilding. If I'm going to include something in my work, I want to portray it correctly, so I make sure to do my research. Sure, it slows me down a little in the research stage, but I enjoy it and I think in the end it makes for a better story. I wouldn't worry about it.
I am curious now, as to the proportion of solo artists who plot heavily to those who plot very little or not at all. Simply because I think it may play a role in the connection someone has to a story. Since I plot everything out, I know all the beats and nuances, twists and characterizations before a single word is written. I only let one or two subplots fly in naturally. As a result, when I am going between drafts and editing it usually isn't a complete rewrite. Also I can go back and look at pre writing notes to clarify intentions. It makes switching between projects at drafts easier.
I tend to plot heavily, but in stages... if that makes sense! So I'll plot the first part of my project, then write it, and as I'm writing I come up with ideas for the second part and make some notes, and when I'm finished writing the first section I plot the second. Then I continue on to do the same thing for each 'segment' of the project. I do lots of research and like to know lots of detail, even if I don't always include it. As I said before, I think this has a lot to do with keeping myself organized.