Bri ... we're having a low Vs high mount theme at the moment.
Richard ... I was just giving examples for my 30/30 ret which I had on high mounts. I used the high mounts as I felt I was ok at ranging up to @ 30 yards and the high mounts flatten the aim points on the longer range targets.
Brian is right that most folk will use low or medium mounts. I started like that and still used 30/30. You just need to figure out what zero works for you, and then where all your aimpoints are for various ranges. Even if using lower mounts you will be able to use the cross plus the bottom bar for all ranges
When I was using medium mounts my zeros were 35 and 13 yards. Using those medium mounts at 45 yards I just put the bottom bar at the bottom of the kill. Again around 9x mag.