The “layout” layer is quite confusing. It is basically meant to offer an option to isolate a set of buffers and configure a set of windows.
This is the workflow I have that seems to work for me (nb: I'm using most of the time projects in their own frame):
spc l <nr>to create a new layout (orspc p lto create a layout from a project)- setup windows and buffers
spc l ssave the layout (asks for a name and file)
spc l Lto load the layout from filespc l <the-above-layout>spc l Lto load the layout from file
Note: it's not yet clear to me why I need to load the layout from file twice, but it looks like the first time it only "initializes" the layer and it's only the 2nd time when it restores the windows and buffers.
It’s some sort of “tab” system per frame which allows each tab to use a different window setup. As of now, I’m not very clear how I could use it, except maybe when working on a larger project and having to maintain in parallel multiple investigation paths.
If you got to this Gist and haven't seen Spacemacs ABC (7), I'm strongly encouraging you to watch this video. It's been the only material I could find that set me on the right path.
idk why this was so hard for me to get at first, this helped a ton!