They count the revolutions and already know mentally how many turns for x amount of yards. Once you get used to doing it all the time it comes second nature.

Example first revolution goes from 25-30 yard start then that one revolution goes to 85 yards then next revolution 120 yards then one more revolution 150 yards and so on depending on caliber weight and speed.
 
You can make your own zero stop if the scope doesn't have it built in from the factory easily in case you want a definitive start point by using delrin washers stacked to appropriate height and file and sand one of them thinner to make the turret cap sit tight when at 20 or 30 or 35 yards. Then all you have to do is count up to 3 or 4. Lose track? Then crank all the way down till it stops then count ONE revolution (you are past 60 yards already) TWO revolutions (you are past 100 yards already) and so on...

If you have a 3d printer you can make oversized turrets with zero stops by adding a grubscrew pointing down and run a pointer or a ziptie tight around the scope tube and adjust till it hits it at start point then test crank 1 revolution it clears it then put a dab of nail polish to keep that screw from moving.
 
Depends on the scope also. My Midas Tac 4-16x44 has 10MIL per revolution. I sight my guns in at 50yds and usually 10MIL can get me out to 150yds which is more than enough for an airgun. Also has a zero stop which I find basically necessary for my scopes now. Then there's scope turret stickers you can use and set different yardages on where they line up on the turrets.