I’ve rarely actually had much trouble coming back to a project I started / played a large role in after a few months (or even years). I’ve experienced what you describe on other projects though, especially if they’re way outside my field of expertise.
Somewhat off topic, I’m searching for a new job soon - are there any good guides or information on design practices you’d recommend? I’m self taught with no college education, and a majority of the work I’ve done has been for SMBs on (mostly) solo projects where I determine the direction to take. I like the flexibility of working for SMBs, however there are a lot of cons as well. I sometimes worry I’m shooting myself in the foot listing just under a decade of experience, but none of it “junior level on a team” where I’d pick up some of those skills.