Yeah, pissed me off as I did 4 stones first and completed the first wave with like three minutes left. I didn't realise you could respawn in the middle until I accidentally wandered into the stone with like 30 seconds left.
Incidentally, another thing that isn't explained, you have to do 4 stones before you unlock the 5th slot in the map device.
And that 5 way run isn't worth running at current prices (~250c /run last time I checked), unless you need the challenge completion. Even with a HH, it's still a gamble with 4 or 5 loot bars as the price of timeless jewels are saturated and there's no effective method to market the sales of good jewels.
You could use that extra map slot to juice your maps a little more, but that's not nessessary as this league is dropping t16s like candy with little investment (sextants only will allow map sustain).
Seems like the best economic stategy is to run alch and go white map like glacier, block it so that only glaciers drop, and then speed farm just the legion monolith by the start of the map and repeat. Sell maraketh and templar splinter/emblems and incubators in bulk for bank.