I.e. it's precisely when you look at these chained that the difference is actually very large. It's really only the 1st turn or two of prompts where the difference seems negligable.
Not to mention that the deeper your iterations, the more money burned on garbage before you realize that data in turned to garbage out turned to garbage in somewhere in the chain.
There's also the matter of "90% compared to what". If it was 90% per attempt compared to a calculator then I'd just use a calculator. If it was 90% per attempt for something I have a 10% chance of getting right per attempt then it's not really so bad. OTOH if it's 90% per attempt at keeping my car in the lane then it's obviously quite bad. I.e. there isn't one "reliable percentage" to target which is why I'm comparing the curve instead of just the most stringent things I can think of in isolation.
That's completely orthogonal to whether you can still find tasks which require more accuracy or not (except for the sole case someone claims it's 100%).
However the origins of theory explored the outcome of disastrous and irreparable outcome of space shuttle exploding, lives lost, and billion of dollars destroyed.
When LLM goes off the rails the cost is much lower, and retry is on the table. In fact our core competency shifted from writing code to creating environment where agents can retry cheaply and course correct based on feedback.
A modest increase in the number of turns it takes to reach decorehenve could make a difference between Decoherence and reaching the a grounded checkpoint.