That talk with an old TV tech made me rethink how I clean boards

I was swapping stories with a guy who fixed CRTs back in the 80s at a shop outside Dayton. He told me he never used a toothbrush or alcohol on a board without first checking the part's heat tolerance with his finger. Said he once ruined a batch of tuners in 1987 by being too aggressive with a scrub, cost the owner $400 in parts. It hit different because I've been dunking phone boards in ultrasonic baths without thinking about what's actually fragile. Now I check every IC and coil for stress points before I soak anything, and I test with a thermal camera if I have one. Has anyone else got a weird rule from an older tech that sounds old school but still saves you today?