MOA adjustment is suggested for longer distances and when you have time to make the adjustment.
Hold-offs are useful for shorter distances or when there isn’t time to make an MOA adjustment.
1 Mil-dot is 3.43 MOA. 3.43 MOA corresponds to the bullet drop at about 275 yards with a 100 yd zero. The bullet drop for 2 Mil-dots corresponds to about 400 yds and 3 Mil-dots corresponds to about 500 yds.
At more than 500 yards, accuracy becomes very important and it is probably best to use the precision of MOA Adjustment instead of Mil-dot Hold-off. For instance, +/-0.2 Mil-Dots accuracy is more than +/-3.5″ at 500 yards and of course increases at longer ranges.