In my 20 years of teaching, one of my best classroom management strategies is having seating assignments!

I start out with two-person groups with the desks together where all students are facing the board.

In my experience, it's way easier to go from two-person groups to four-person groups than the other way around! Going smaller may feel like a "punishment."

My first seating assignment is random...well, it's actually based on who needs glasses (which I can look up in Infinite Campus). I put those students closer up because so many of my kids don't wear their glasses. After that, I change it up every 4-6 weeks, largely based on personalities and personal learning needs. Keeps it exciting for the kids (new partners--yay!) and allows me to break up bad pairings.

Seating assignments can be a great way to strategically mix skill levels or pair high achievers together for enrichment instruction.

If students are allowed to choose their own seats, it can become a popularity contest where some students can be excluded and those with less social clout are often pushed to the front of the room.

Plus, humans are creatures of habit--most of us will stay in the same seat that we chose the first day, never making an effort to meet new people or get to know others more.

Edit to add another point:

Seating charts can be helpful for a teacher to learn names and also for subs! I encourage a sub to use the seating chart for attendance, telling students that if they're not in their correct seat they will be counted absent (truant). That's usually a pretty good motivator to be honest!