I didn't think there were set distances; convergence is about regulation; regulation is about dealing with muzzle jump, recoil and the "up and away" recoil continuum, muzzle velocity/barrel time etc. All of these variables are affected by the characteristics of the individual gun and load, and trial and error is the way to get there.
I guess there would have to be some ball park figure to start with though, and a quick and dirty rule of thumb for lower grades which will never be indulged with that time-consuming regulation process.
RG
