The rules you have mentioned apply to SHOULD be at a PC screen for, for health reasons. They are different ot how long you DO game for or can game for!
Personally, I am in front of a screen from 7.30ish to 5ish at work everyday or the same at home if on holiday. Then at home I play SWTOR (previously Warhammer Online, Skyrim, Oblivion etc) for as many hours as I can a few times a week. Generally 3 nights from 7pm till 12.30/1am. This is solid time with Bio breaks and wife bothering me only, Diet Coke bottle next to me for sustinance.
In the past when the wife and son have been away and I have been off/holiday I have done 6am till 3am with Bio/Food breaks. But not at regular or good intervals, maybe 20 mins at midday, the rest in game.
I do stop if I start to feel strange, normally have a bit of a walk to the shops to get some more Diet Coke or munchies. I do consider it unhealthy at times, but no worse than sitting down in front of the TV for hours on end watching rubbish.
I'm glad that I did play WoW though because I gained some guild friends who became real friends in the sense that I see them a few times a year and write to them every week even though none of us play the game any more.
I have only met one guildie face to face, but he was my boss at work so I got him into the game anyway! The really strage thing was speaking to another english guy in guild I learnt he lives a few miles from my work! I have been playing with the same core people for 3 years+ now and consider them mates, we live too far away (Sweden, Denmark, Holland, Norway, UK, Hungary, Romania,) to see each other really! We even kept speaking on Vent when we stopped Warhammer and moved to Star Wars. We were all playing different games, BF3, Skyrim, Civ5, World Of Tanks but just chatting!