First, I can shoot a ladder off the back porch and am going to spent at least 1.5 hour to shoot groups. If I could shoot a decent distance right next to the house, I would probably try shooting groups to see if it was worth the additional hassle of shooting targets. Also, I'm looking for good SD and a wide flat spot when charting powder weight vs velocity. In your example, I would use 60.3 without even checking groups for 60.2 or 60.4 unless 60.0 or 60.6 also give good SDs and comparable velocities. I do this because it seems likes picking a value between 25% and 75% of the flat spot range gives you a consistent recipe even though it may not give you the best groups on a particular day. I've been burned before pursuing finicky loads because they showed a good group in a ladder so I try to do everything reasonable I can to stay away from them. I know if the rifle shoots .75 MOA, it isn't the limiting factor in my hands and I can usually get .5 MOA pretty easily with this method so that is what I use.
If shooting groups @ distance was convenient and I changed out my magnetospeed to a option not clamped to my barrel and I had a ladder of three consecutive charges with consistent velocities and the middle group had good SD and tight group, I would go with the middle group and call it a day. Right now for me, shooting for groups during a ladder test isn't worth the extra effort.