Docs in a browser window, next to an editor window, while working with a library that isn't very familiar. Granted, this works better on a display of meaningful size, but I do it a lot and vertical tabs would waste noticeable space.
On the other hand, I have good tab discipline in general, so vertical tabs would waste even more space by virtue of dedicating a lot of real estate for displaying next to nothing. But who needs all those tabs anyway?
While doing research, each search yields numerous links that I need to evaluate so I'll open them all in tabs and then I go through them as a task list to whittle down.
I have a whole window for just email + comms. I have several different businesses that all use separate email, etc in containers.
I also have several interests where each gets its own window and has up to 24 pinned tabs of key sites for that topic. These are not business, so I don't have time pressure to whittle down the tabs that I open.
I currently have 368 tabs open and they are all easy to access: Select a window by topic (I use the Titler extension to name windows) and I have 3 rows of 8 tabs pinned at the top and up to 37 tabs with 40 characters of tab name space. So in each window, I can see 61 tabs without scrolling.
“ I can’t imagine why anyone wouldn’t use vertical threads”
“ doesn’t work on small screens”
“Get a bigger screen”
Consider that most people don’t care to even if they have the money. I sure don’t care for a bigger screen. I find myself more productive in a small screen anyway.
On the other hand, I have good tab discipline in general, so vertical tabs would waste even more space by virtue of dedicating a lot of real estate for displaying next to nothing. But who needs all those tabs anyway?