I've been teaching for 13 years and can firmly say that unless you have a class exactly where you want them classroom management wise, putting them in large groups facing each other, in pods, at secondary level, permanently, makes managing behaviour *very* difficult.
My default setting is rows or a horseshoe, it's great to say "this works for collaboration", but without behaviour being "right" it's pointless. I'm fed up of politicians (and others) who don't have a clue theorising about this. That's what it is - a theory! practice is different
The basics - if students are sat in large groups, they are often facing each other, meaning distracting and being distracted becomes a lot easier. Second, if all work is collaborative, some will excel whilst others will rely on others. Tracking *everything* becomes harder.
Learning - Well, I do like group work and collaboration, but if students are sat in rows at default, you can easily say "stand up and move to a group for 5 minutes to discuss X". That gives you a "get out" if it goes wrong. Equally, its short and sharp and focussed.
Saying to trainees and new teachers "if you don't have students sat in groups or working in groups all the time you aren't promoting collaboration" is a dangerous tick box approach.
But this is the point - nuance is important. Gavin - rows all the time. Kate - Groups all the time. It's not healthy. Teaching is complex and teachers need complete autonomy to do what's best for students at that moment, not be judged from outside on a set of theoretical ticks.