At the largest bank I worked with. Trac was the primary wiki that was in use for almost 15 years (largely abandoned for the last 5). Think 10 000 wiki pages and documents written by a thousand developers over the span of entire careers. Note that Trac is abandoned software, for example it cannot run on python 3, there's been issues filled on that for years and there's simply no effort to maintain it.
I decommissioned it last year (hint: there's a long and painful migration story here). Users and documents have migrated to Sphinx, that's been actively used for the past 10 years and was always supposed to replace trac (hint: there's a longer story on how to handle or not handle a migration here). It looks really good but the markup and editing tool is not really user friendly.
A few teams decided to move to the internal confluence instead, that's supposed to be the strategic solution in the company. Looks like they're up for another migration within 3 years.
We were using it up until a while ago (edit: oh, did the math, 7 years ago)... could still totally get by with it.
I keep my free Jira/Cloud account going, but when I look elsewhere, I don't really love the options either (Clubhouse, looking at you).