The main thing to keep in mind is to give yourself room to work them. I used to put them in groups of two, with more space between those groups. That way I could work one from the right, one from the left. I started leaving more space between each hive when I wanted to start doing more side-by-side splits.
no rules on spacing as said before give yourself room to work them. If they bees drift to a certain hive switch it out with a weaker hive in the middle of the afternoon when the bees are out foragaing. This will help balance out the nunbers
I have my three hives separated with 50 yards between each one. You may not have that much room but it helped me get "user friendly" with working the bees. It just seemed like good planning when I started to inspect my bees to have less bees in one concentrated area with a new beekeeper learning the ropes.
I've also noticed a considerable difference in the color of honey from the two hives that are on each end of the 100 yards. I have removed two supers of honey thus far this season, one from each of these two hives and the honey in one was a dark color and the other almost clear.
I've never used an entrance reducer or had any robbing problems with the hives separated. Some and maybe all will say that has nothing to do with it but so far so good is the way I look at it.