sit or stand
Depends on the reloading operation.
For lubing/sizing, I sit. The bench is at that height. Same for case prepping - the RCBS machine is on the same bench.
Two Dillons and a single stage press are mounted on the bench design from the US reloading association plans. I first made it high to prevent my young son from fiddling. This necessitated sitting on a high stool, which I did not like.
When he got older, I lopped several inches off the legs and now stand. An old hand once told me - "When you're too tired to stand to reload, you're too tired to reload." This assumes no physical infirmity, of course.
I find that he was right. My concentration suffers when fatique sets in. The first time I make an error, fumble a case, spill, powder, etc., it's time for a break. Reloading is a 'heads up' job.