In my opinion....6 hours or so should do just nicely!!! Ofcourse it all depends on the nature of your real life job. Taking out 2 hours each in the morning, noon and night is just about enough to satisfactorily do the following;
1 complete daily tasks...earn your VPs
2 check up on your downlines...communicate.....study the learning material available
3 head on out to tripleclicks....play some games...earn some MRPs along the way
4 work on your marketing skills..etc