Testing is an issue, yes. Making sure my tests are comprehensive, making sure my environment is set up in a way that makes the tests valid (that is, that I'm going through the right code paths) and verifying such, remembering where all the appropriate checklists are ("oh, right, that was testing a Y, I need to do checklist t_Y"). I occasionally have to make an extra commit because I forgot to stage a line or a comment. Stuff like that.

I've largely dealt with it by moving into CS theory and AI (which have less of that) and by using Google's reminders system (inbox, now, keep) to deal with the remainder. Just, whenever I have to do engineering, it's always going to be more difficult for me, and since I'm damn good at math there's no real reason for me to focus on engineering beyond the level where the other things I'm doing don't take hits from it. And unless I manage some kind of transformative pivot or redefinition, it'd be pretty stupid for me to focus on being a great engineer, and I'm not sure I'd be able to. I certainly am never going to be as good an engineer as I could be a computer scientist.