Bled every radiator in the house for the first time and now I'm weirdly proud

Heating came on last week and the upstairs radiators were cold at the top, which I learned means trapped air. Ten minutes with a radiator key, a tea towel and some hissing later, they're all hot top to bottom. Then the boiler pressure dropped to almost 0.5 bar and I had a small panic before figuring out the filling loop. What's the small seasonal home job you wish someone had told you about earlier?