I do 100 yard zeroes using 25yd targets marked appropriately - example:
I just put them on a USPSA or NRA Action pistol target and shoot at it at 25 yards. Very rarely off paper with a new optic. Just use a ruler if needed to measure windage and elevation, convert that to whatever your optic uses.
So, target up, 1 round, measure, adjust, 3 to 5 rounds, adjust, 3 to 5 rounds to confirm, then off to the part of the range that allows me to shoot 100 + yards to verify zero on paper and practice holdovers on metal.