Like most here, it's one of the only features that I must have in a rifle scope. If you dial frequently on the clock, it's simply a necessity to eliminate one less possible error (wrong revolution) and get a zero, or worse, dq'd for errant round into space.
If just range plinking, not necessary but very useful. If your shooting at 1000yds with a 6.5CM (say 30MOA/8Mil and end up one full rev off, depending on how much elevation per turn, you could send a round as far as 1350 to 1500yds down range. That could be disastrous depending on where you shoot.
It's just like anything: train right, train often and you can learn do a lot with very little. But a zero stop gives you a firm reference point for knowing your at the right number on the dial.
On the bright side, virtually all scopes designed for long range use from $600 and up include some form of zero stop. There's no good reason to choose a scope that doesn't have one unless you need another feature on a specific scope for some reason (I can't think of any offhand).
My scope feature checklist in order of importance:
- Zerostop
- FFP
- Reticle matches needs
- Optic quality/clarity for my eye.
- Correct magnification range for purpose
- *
- *
- *
- Budget
If a scope doesn't pass those tests in order it's permanently off my list; all that do are on my shortlist and they become options to get hands on time with when possible. Notice budget is behind three empty spots: this is because if what I need is beyond my *current* budget, it just means I need to save more to ensure successful build/meet goals for build.