Sometimes the power ring will jam the adjustments when the power is adjusted to the end of travel, so it's best to back off just a tad once it hits the end of travel, then when adjustments are made at the turret, the reticle can move as it's adjusted instead of moving a little at a time with the recoil. I always tap on the ring cap after making adjustments just to make sure the reticle moves before the shot and not afterwards, I do this on all scopes, not just bargain scopes, doesn't hurt and saves a lot of frustration. Scopes that aren't mounted in lapped rings are likely more prone to issues since the scope tube may not be mounted stress free, this can cause issues too.
Tim