I use mine to compare what few factory loads I shoot do in comparrison to my handloads. In most cases I try to stay within the velocities I get from the factory but for a few rifles there isn't any factory loads. For those I am simply on my own but I DO stick to within reason, and don't try and get overly rambunctious with things.
I've been at it long enough to know when a velocity for a certain load is pushing things, and that is another good thing about having the chrony out in front while working up loads.
Mike / TX