I used to be a tree-style-tabs power user but at some point I went back to regular tabs. I find that the amount of horizontal tab space is pretty close to the actual number of things I can usefully have open at once. Seeing the tabs get "squished" is my reminder to close the ones I no longer need. I was using the tab-state as a sort of short-term working memory and I don't think it was doing me any favours, particula…
These days I want to split my window in half and have two windows open at once, e.g. code editor & browser/shell/etc.
In general, I prefer having a search interface to my tabs, previously with Tabli, but now it's built into Chrome with Ctrl-Shift-A. I regularly have dozens of tabs open though.