Smoking without wood chips
The meat doesn't really "absorb" the smoke, as much as the smoke sticks to the meat, for the most part.

The real answer here is strictly what your preference is. While there are some preservative qualities that are delivered through smoking food, you should consider smoke a spice no different than salt, pepper, garlic powder, etc. Smoking food for two hours should be plenty for most people's palates. It is better to be a little light on the smoke than a little heavy (I know this from my own mistakes in the past).