My sessions start off as short-ish ones of about an hour or so, but soon descend into four or five hour ones with breaks for the toilet and food when they are needed.

It's not unknown for my girlfriend to call at 7pm and realise I'm playing and then call back at about 10pm only to openly question my sanity at _still_ playing. Half the time this is because I am ahead and want to ruin people and the other half is because I have reloaded and want my money back.