I honestly don't know, and it'll be subjective. I would think one every 2-3 years would be realistic. Regardless of how you view the hierarchy of rounds, you're going to draft like 15-20 players during that period. I don't think expecting one or maybe even two during that period is unrealistic.
And I'm not talking like HOFers necessarily either. I don't expect us to land Ray Lewis or Ed Reed every 2-3 years. But guys that are like universally top like 3-5 players at their positions I think is reasonable.
And I'm also OK with it being in batches. Like 2018 you landed 2-3 complete studs. A top 5-10 QB by every metric, a top 2-3 TE and a top 2-3 RT (now a high-end, soon to be highest paid LT). That was in one draft. Some years you'll have none, some years you'll have multiple.
i think when you average it out over time then 1 every 2-3 is probably fair - but i think that only works over the long-term and not many GMs make it to the long-term... only 12 current GMs have been in their post longer than 4 seasons (5 drafts at this point although none of the 2022 drafted players have played yet obviously)