Have you ever just assumed more data would be overkill and regretted it? I used to totally buy into the "start small, iterate fast" mindset until I wasted a month on a tiny dataset that had garbage accuracy. Now I just throw more data at the problem from the start and it saves me way more time in the long run.

Absolutely, you hit it. I had a Whirlpool last year where the manual swore it was a bad thermostat, replaced it three times before I found a cracked wire harness that was messing with the readings.

Was he using any kind of filter on those fans?