I know a cardiologist who gets eight weeks of vacation but so do his other practice partners. When he is on, his is fairly busy though. And he lives in a fairly small city - where you need these types of incentives to attract docs.
The problem with giving more time off to just one doctor in the group is when you are gone, someone will have to cover your inbasket. If its a bigger group, they can probably absorb the 10 weeks of inbasket coverage by spreading it out but if you only have one other practice partner, it may seem like too much of a burden to him/her.