Typically, formatting plain text documents that aren't source code. I also want to use the tab key to make a tab character, though. I suppose that I could reprogram the tab key so that holding it down repeats spaces, but that's straying too far afield for my tastes.

I can see how this scheme would be excellent for some, but for me, I'm pretty sure that I'd be happier making the fn key something else.

For that, I prefer to configure the editor to convert tabs into spaces, so I still use the tab key, as this is faster.

I don't always use the same editor, and some of the editors I use can't be configured like that. But I'm curious -- what do you do when you want tabs?

I never want tabs in my files, as tabs render inconsistently across viewing apps. Tab characters are like nondeterministic spaces, so why would I use them?

Some things require tabs, like Makefiles. My editor (vim) is smart enough to know this when editing a Makefile and do the right thing.