I haven't had great luck with the melpa plugins, but I'm probably going to try it again here, maybe things have gotten better in the last couple of years.

Running `grep` from the root of my Org directory gives me access to about 10 years of notes from various projects across various organizations. In hindsight, I could have tried to periodically dump things out of my clients' various project management systems for historical reference, but just using Org on its own has proven pretty effective at that :)