The formation of the smokering is a chemical reaction that takes place between 40 and 140°. The longer the meat is in that zone, the more pronounced the ring should be. That is not to say, however, that one should make a pronounced smokering a goal-- there are food safety factors to consider in that particular temperature range. Other factors, such as oil in a rub or surface fat may inhibit the smokering.
Smoke flavor is another matter altogether. Meat doesn't really "absorb" smoke. What's actually happening is that smoke is being deposited on the meat-- the longer you apply smoke, the smokier the taste. Therefore, it is possible to "oversmoke". So, if you wish to finish in the oven, or elsewhere, you can be fairly certain that the first few hours exposed to smoke will be more than adequate.
