I currently use what would be around half my salary at the currently listed full API prices (which I doubt we'd ever have to pay but lets assume we did), and a decent portion of that is experimentation, learning, wastage etc. I could cut it down to a third of my salary if I was more conservative. And I'm building 3x more features than I was without it. That's a good deal even at full price, it's just even better now with the subscription which is why the smart thing for any engineer to do right now is to take advantage of those temporary heavily subsidised prices to get as good as they can at agent accelerated coding