This is a fairly simple question....I hope...

I have an older (like 20 yrs) Hard Rock MTB that's still well-maintained and in fairly good shape (ride it 3 times a week). I've been thru a couple of free hubs, cassettes, bottom brackets and crank assemblies. It's all pretty much been Shimano Alivio class, so more low end. Even tho it's an MTB, I rarely take it off pavement (I do have some favorite "short detours" on smooth-ish gravel paths, tho) and it's fairly flat riding.

Assuming chain and crank are new, rear der fairly new, how many miles could I expect to get out of a lower end cassette (like Shimano HG-4X or HG-5X, 11-28).

Thx in advance for you feedback......