Exactly! This was my go-to approach for reducing storage costs. Customers don't get spooked when they get an extra 1s delay for something they search once in a month. However, an extra 30ms delay in "everyday content" is a sure way to loose your users.

However, implementing this in practice is non-trivial. Knowing what is "everyday content" versus what is "once a month content".

To add more complexity -- you have these semi-predictable hype-waves especially two peaks in case of most YT videos where a "once-a-month" content becomes an "everyday" content before again becoming a "once-a-month" content. It feels you could specifically optimise for this -- reduce storage costs without sacrificing UX.