Looking forward to what you come up with, @fkaye.
I played around with @Paul_Storry's concept a bit and came up with a somewhat wacky way to get close to the workflow I think you want: collapse-groups. You'd navigate this by selecting a section you want to fill out, filling it out, swiping back, selecting another section, etc. The select one acts as a kind of table of contents. Then, at the end, you can pick which block to actually save. Presumably, there'd be a bunch of questions between the table of contents and the final select. Like I said, it's wacky and I wouldn't recommend it but maybe it gives interesting ideas.
This also connects to questions of form linking (Linking different forms) and non-linear navigation through the form. One possible approach would be to make it possible to create links to any specific question in a form.