> YAGNI (You Aren't Gonna Need It)
This one is listed as design, but it could just as easily count as architecture. Guessing a lot developers have worked on scaling with lambda functions or a complex IAC setup when a simple API running on a small VPS would have done the trick, at least until enough people are using the application for it to be considered profitable.
When we dockerized a service the p95 time in testing notched up a noticeable amount. I was already juggling so much other work at that point that for shits and giggles I tried vertically scaling - reducing the cluster size by half and the cores per server by 2x. Zeroed out the p95 delta.
OPS gave me shit about it, and I was like kiss my ass, the cluster costs EXACTLY the same and deployments are 25% faster.
I think people forget that in the cloud, bigger servers don't really cost more until you get crazy about it.