There is no simple answer to your questions because of so many variables.
Fruit Woods like apple , cherry, pecan, grape, are very mild woods so I keep the smoke going all thru the smoke. I have not experienced too much smoke in the meat and only occasionally there is not quite enough.
Hickory is a little stronger so I might keep it going for 4 hours out of a 6 hour smoke.
Mesquite which is quite strong I probably will just use for the first 3 hours or so.
Basically you have to taste the finished product and determine if it did not get enough smoke or got enough smoke or even sometimes if it got too much smoke. Then MAKE A NOTE OF IT. Note the type of meat, the temp you used, the type of wood and how it turned out. All smokers are a bit different. Only by taking notes will you ever get it just right for your smoker. If 3 hours of mesquite was too long but was nearly right cut back a 1/2 hour to an hour and make another note. You will be surprised at how quickly your smokes will begin turning out just exactly how you want them. Each wood is a bit different, you have to make sure that they are cured enough or your results will vary greatly.
In my experience fruit woods can go thru the entire smoke.
The Guru's on here have told me that most of the smoke is absorbed by the meat from when you put it in the heat up until the meat reaches 140F but even after that point the meat continues to absorb smoke just at a lesser rate.
Also if you start the meat at a cooler temperature this gives the meat a bit longer to absorb the smoke before it reaches 140F.
Some folks say that if you can smell the smoke its smoking.
I like to be able to see the smoke coming in a steady stream of thin blue from my smoker. Not always easy to see if its windy.
Billowing white smoke is bad, thin blue smoke is good.
Some folks like to soak their wood but others do not. This is a Huge controversy and I have found its better to stay out of the oft times heated debates surrounding it.
Some folks use a mix of soaked wood and dry wood. The dry starts smoking first giving off its goodness then as it begins to dry out the wet then begins smoking thus giving a longer overall smoking period than just using dry or wet alone. Some folks swear by this method. I just keep adding dry when ever the thin blue begins to lessen out the vent. Works for me.
Your answer then lies within yourself, only you can determine how much smoke flavour you like. Then you have to do a few smokes till you figure out how much time it takes and what kind of wood you like to get to the answer that is right for you. As soon as you do that, a wife, a child, a relative or friend will want it smokier, less smokey, or a different wood. Thus will begin another journey to get it just right for them. It never ends and is part of what makes it all so fascinating.
