Yep, I like adding some space between windows.

I proposed something like that for spectale some weeks ago. Got refused. https://github.com/eczarny/spectacle/issues/290

I mostly use apps in fullscreen and sometimes need to see 3 /3 apps at the same time, then switch to fullscreen, then back to tiled mode again...

Small aesthetic gaps around windows may not be such a waste of screen estate.

Window spacing is actually in the works for Amethyst. It just has some issues because some windows just don't size exactly. Terminal windows, for example, only size in increments of cursor size, so you're almost always a bit smaller or a bit larger than you want, which makes the spacing in between windows look weird.

I noticed that with or without my spectacle patch.

I tend to prefer uneven gaps than no gaps though, considering how unpleasant overlapping drop shadows looks like.

You can theoretically turn off window shadows. https://github.com/puffnfresh/toggle-osx-shadows