I've had a crack at a few laddered shafts and the major wait is waiting for "Clear!"
The lower bits of consols were about 270F down from surface. So call it about 500M.
So, 500M/90m = 5.55M/m so 1m every 11 seconds or so.
Bearing in mind platforms, stops to catch your breath, fiddle with your candle, wait for "clear". That's feasible.
I like the quote in "Exploring Cornish Mines" about Consols. It must have been an unbelievable place. Some hooray henry rocked up and described what he saw.