When I first started, I was in a room with 8-9 people who knew each other well. They talked a lot. I was given a task that I found challenging but the most challenging part was focusing on the task at hand.

My solution was to listen to one of various white noise videos on YouTube, my favorites were storms and rain.

I agree that about 5 people in a room is a perfect fit. Team sized. Open spaces were too distracting.