There are moments where I have a 2 hour , 4 instances in separate Kitty/Ghost windows , Opus 5.5 hammering away on each - and only see a 1% increase on my Max x20. Then there are other days where 10 minutes of a single xH Opus doing 1/10th of the work will kill 2%.

Anthropic is super opaque with what inference costs at any given moment on the subscription and cache is just super inconsistent.