That depends on a few things.
1. Does your carrier offer no forced dispatch.
2. If you drive for a fleet owner how often are they comfortable with you being out of service.
3. Profit margins are tight. If your not driving your not making money. How often can you afford to be out of service?
4. You may be able to ask to take loads going in a certain direction but you're subject to where the freight is going. How much deadhead are you willing to drive to get home?
That being said I would think the average driver is away from home for 2-3 weeks at a time.