Dont worry with shark shaped teeth and chain checkers. The first time one gear slips, change the lot. It will probably take 3ish years of riding 2-4 times a week like it did on my Jeffsy for it to do that.
Easy and simple.
Definitely easy and simple, and plenty do it, but there are a couple of disadvantages. For me, the biggest is that once a chain gets beyond 1% wear (and less with modern 12-speed groupsets), you’ll never be able make a new one work as the rest of the transmission will have also worn to the same amount. This is fine if you manage to ride it into the ground, but if you ever trash a chain and need to fit a replacement, you’ll be facing an immediate, expensive bill as a new chain almost certainly won’t work…and if you’re somewhere remote, good luck getting the rest of the bits anyway!
The other one is simple mechanical fatigue. I rarely (never in the last 10 years) snap chains and I’ve put this down to being pretty rigorous with maintenance and retiring them. A snapped chain is a pain in the arse and, if it happens at the wrong time, probably uncomfortable and potentially dangerous too. Each to their own, but the chain (and wheels too) is something that I’d keep in perfect condition.
Each to their own, as you say, and others have argued long as to which is the most cost-effective route, but it’s not quite the simple choice you make out. Also, who really keeps spreadsheets? I just measure the wear on mine from time to time and if it needs replacing, I replace it. Cheap and takes < 5 mins. No stress.