If you're shooting a ~3,000fps bottleneck rifle round, 200. If you're shooting a .45-70, then 100. For most standard and magnum rifle cartridges, you're looking at a ~250-275yrd MPBR for a 200-230yrd zero. Shorter gives a smaller variance, longer gives larger, and if you're dialing every shot, none of this matters - but if you only want to dial 300-500yrds and hold dead on or slight hold over/under without dialing from 0-275, get them at 200.

To be honest, it's all arbitrary anyway - your zero doesn't matter, just need to match the turret to the range and it'll be zeroed for that given range.