Unless I am playing werewolves, I do not spend much successive time on the Downs. When I'm home, I just check every hour or so - see if anything interesting happened. About an hour or two a day in total, I guess.
I work on the computer a lot - translating and all that - so I'm often around to check if I got any PMs, but mostly focusing on other things. Or at least, attempting to focus on other things.