This was my philosophy going into the iPhone X last year on iUP. I guess this year I reached my own personal limit-- while I'm sure I could afford the extra $12 it would be to jump to 512gb Xs Max, it's starting to feel a little ridiculous (both the individual monthly payment for the phone and the overall price, especially when you figure AppleCare+ in there...) and I have historically *always* jumped on the maximum storage Apple would give me. First year not getting the very most expensive iPhone for me.The only reason I am doing 512 is because I am in the upgrade program and it's just an added fee to my costs each month. I would never flat out pay for the 512, I'd by a laptop.
On the other hand, if I was feeling tight on space with my current 256gb, I'd probably have already reserved a 512gb device
The kicker is AppleCare+. I have never had to use it, and only started buying it with my first "Plus" sized phone because I knew larger phones were more susceptible to screens cracking in general. If I had the option to finance at 0% and trade in every year without paying for AppleCare+, I think I might be tempted to use that $200 instead to get the 512gb model.