This phenomenon occurred mostly when I was a teenager and young adult.
Typically it centered around one popular group of kids and their parents, kids were never allowed to sit in groups by themselves, at least, not for long.
So, everybody tries to get seated next to the people they want to sit near, usually an amalgamation of trying to get next to girls or guys you are interested in, mixed with some JW social climbing etc. etc. Having a seat saved for you with a popular family was a big coup.
Did this go on with your social groups and the assemblies you attended?
hugs
Joel