100 yards if that's your distance for load development, that's where most of us do it. For seating depth, don't get into the weeds. Start coarse, find the trend, pick a spot, be happy. I start at .010 off the lands, then go to .040 off, then .080 off and then .120 off. I've never found anything that likes .120" jump. Most things like between .010 and .040. If it likes it better at .010 than .040, then try touching and .010 jam noting that pressures will almost certainly climb so if you're flattening primers at .010 jump, probably don't go jamming or even touching.
Boxtobenchprecision.com has a fantastic load develop,ent target that gives you the jump distances I listed. It's made my load dev process much shorter.