[Question] What are some triggers that prompt you to do a Fermi estimate, or to pull up a spreadsheet and make a simple/​rough quantitative model?

I’m currently viscerally feeling the power of rough quantitative modeling, after trying it on a personal problem to get an order of magnitude estimate and finding that having a concrete estimate was surprisingly helpful. I’d like to make drawing up drop-dead simple quantitative models more of a habit, a tool that I reach for regularly.

But...despite feeling how useful this can be, I don’t yet have a good handle on in which moments, exactly, I should be reaching for that tool. I’m hoping that asking others will give me ideas for what TAPs to experiment with.

What triggers, either in your environment or your thought process, incline you to start jotting down numbers on paper on in a spreadsheet?

Or as an alternative prompt: When was the last time you made a new spreadsheet, and what was the proximal cause?