When I was hunting the 3090, in general I polled every 5 minutes (with some variability to look more natural). When the "official" release time came closer, I brought it down to something like 1-3 minutes. I never ran into problems with IP blocking.

Trust me, there are people sitting there refreshing the page more often than 1x per minute, and as far as I know they didn't run into any blocks either.