I do loosely keep a log. I use a sublime plugin called plain notes (or simple notes? I don't know).
I used to think it's a great idea to log everything, but now I've resorted to trying to only add to the logs whenever I think I can benefit from the knowledge later.
It has definitely been very useful, I now have tons of notes on useful regexes I can use to search for very specific code patterns, tons of details about sql-injection preventions, optimizations, language features, etc...
I love the idea of working on a base of knowledge that gets sturdier and more reliable as more time goes on. It is a materialized kind of growth.
Most people would probably want the more powerful extension[1] which also has wiki link navigation, but it also has some incompatibilities with my setup.
I use a wiki-ish repo. A Journal.md that is my primary work log, but I also make little subpages when I want to expand into something specific or reference something previous.
So, I might do [[2018-10-11_issue_cron-aws-replication-issue]]. If the issue is more complicated, I would just roll it into a more general [[issue_cron-aws-replication-issue]]. I usually don't need to do this, and I try to not let it grow to be too complicated. But having it be somewhat structured has been really helpful. The links can act as tags, and I occasionally use symlinks as redirects. My Git.md page has lots of things I've learned at this job in it.
I keep it synced with my private git repo[2], where the Markdown wiki syntax works seamlessly with the Gollum wiki[3]. This also works if you want to access your wiki hosted on a private github repo.
[1]: https://github.com/SublimeText-Markdown/MarkdownEditing