Pretty much agree with everyone else, but I'll add that what a "50-yard zero" is really attempting to approximate is a rough 200 yard zero that then should be confirmed at that distance. Without re-hashing the old argument I'll just use the colloquial "50-yard zero" terminology.
What you basically did was stop the process short. The correct full process is:
- get on paper ~1.5-2" low at 25 yards
- get POI=POA at 50 yards
- get hard, true, zero at 200 yards
- verify at 50
- shoot at various distances to check hold-over/under
If you stop at step 1, is it good enough? I don't know, good enough for what? If you stop at step 2, is it good enough? I don't know, good enough for what?
Remember that with angles you're multiplying the adjustment by the same factor as the distance, so a 4" group at 50 yards that *appears* to be centered but is actually 1" left will turn into a 16" group at 200 yards that's going to be really hard to nail down and will have a center 4" to the left, meaning that depending on your target size it will lead to the majority of rounds being "misses".