I avoid new construction too, but since I really only do service work anymore, I encounter a lot of problems with installations done by others. Most recently, I went to a pretty big house (2 yrs. old) that had three 200 amp, 40 ckt. panels. The original EC put all heavy loads (furnaces, heat pumps, ranges, etc.) in one panel, GPA and medium-duty circuits in the second one and all lighting/SA circuits in the third. There were eight AFCI breakers all together on one side of the panel that were tripping randomly and for no apparent reason. These were Square D QO panels.
I couldn't find anything wrong, so I contacted Square D. About a week later, they contacted me and suggested that I separate the AFCI breakers by one space to see what happened. There was plenty of room in the panel to do this, so all I needed to do was put in some blank filler plates. I wasn't crazy about doing this since it threw the load balance off, so I did the same thing on the other side of the panel with the standard breakers, just staggering them on opposite poles.
We never had another problem after that. They suggested that we try to minimize grouping AFCI breakers side-by side for more than two at a time due to potential heat. I never followed up after that except to stick to that rule with any brand from there on-out.
I'm a bit of a perfectionist, so I'd prefer to keep all similar breaker types grouped together. I like to start at the top with the two-pole breakers, largest on top. I then like to start at the bottom of the panel with single-pole 15's, then 20's above those. Any blank spaces are left in the middle so growth can fill in while still maintaining this arrangement. I guess I'll have to adapt.
