My experience is that open office productivity depends an awful lot on who is in the office.

When it's just people coding, normally interruptions are things that make sense. How should I build this or that thing? Where can I get help with X?

However, for many years I had a guy in the office who was a pontificator. He would read some news article and start a debate about (inevitably) politics. People would get drawn into it due to his particular style (very opinionated, uninformed) and the debate could easily eat up the entire morning or afternoon. He would literally stand up and announce some funny point he'd come across, loudly.

Ate up enormous amounts of time.