It's the job of the organisation to tackle this via policy - I've worked at companies where the policy is that if a conversation is anything more than a few exc

It's the job of the organisation to tackle this via policy - I've worked at companies where the policy is that if a conversation is anything more than a few exchanges, it should be taken to a meeting room, and everyone is required by policy to point out to others if they've forgotten the policy and strayed into a long open conversation by mistake. It worked well. Same company had a rule about holding onto the handrail when using stairs, and not walking with drinks that don't have a lid on. And everyone is expected to point that out when others do it too. When everyone buys in it works well, and people thank you when you do point out that they aren't following policy. I'm normally pretty juvenile and rebellious to rules like this, but when it's done sensibly and sensitively - and when the benefits of following the rules are obvious - even I will conform without complaint.