16 volts connected is plenty high enough. Remember the actual equalization formula is to attain 16.0 volts with a 5% of amp hour capacity amperage limitation. Example 11 amperes at 16.0 volts for series 6 cells of GC220 battery.
How long the equalized battery stays equalized separates good battery brands from the pretenders. If there is anything on the face of the earth more revealing about the quality of a cyclable battery I am not aware of it.
From experience, I know a majority of GC owners have no idea that their 220 amp hour capacity rating is actually a lot lower due to sulfated plates. It's only when capacity drops even further to the point of in-your-face weakness that the RVer has the light bulb glow above his head. Of course the proper diagnostic use of an amp hour meter will show any loss of capacity. A hydrometer dip screams any chemical malfunction.
I have had to keep scumbag brand GC's at 16 volts overnight to see gains in electrolyte density. An overwhelming majority of these almost new batteries resumed uneven gravity readings almost immediately.