I can never decide how I want to set this. Most sites recommend 180 seconds or so, but with the default ServerAliveCountMax set to 3, this is 9 minutes before a dead terminal is actually disconnected.

I've started to set it really really low personally - like, 5 seconds, so the connection drops after 15 seconds. I'm tempted to go down to 1, but I have a lot of long running sessions and I start to worry about the traffic counts.

But, after all this there's still a problem: none of it seems to work with any of the connection mux'ing options - once the background session dies, I still have to manually kill it to get anything working again.