Hi Steve,
no science from my corner. I try to keep notes, especially for my my "less good" results, and often these are tied to what I call cleanliness of the smoke.
I can produce TBS. ( Thin Blue Smoke) on my BGE, my WSK, a Kettle and a WSM when I had it. My Pellet never had TBS, it was always more white and puffy.
I can also produce TWS ( Thick White Smoke ) and I can create Brown, or Black or Dark Grey smoke aka dirty smoke. If the smoke is dirty, I won't put food on, and I am cooking and something goes off the rails and I start to get dirty smoke, I pull the meat, fix the smoke and then put the meat back on.
In my experience ( and my opinion ) cook that have TBS, especially long cooks taste better. When I cook tri tip, I cold smoke it using smoke generator with no coal lit at the beginning. The tri tip is enveloped in pecan wood TBS from pecan for an hour or two before I light coal. This method leaves an almost sweet flavor of smoke on the tri tip, even thought the overall cook time is about 3 hours.
I have cooked chicken when I was in a hurry and the smoke had not yet cleaned up. It was on the edge of dirty/thick white and it was over smoked and bitter. I've done the same with Tri Tip, and it tasted like that liquid smoke you can get in a bottle, but too much. Based on that "less good" cook, if I find myself late to start, I'll just change plans and cook on the gas grill, or change a slow smoke cook to grilling.
For longer cooks, and for cooks I absolutely want to smoke over coal, I pad my schedule with at least an extra 30 mins to get the coal started and stable.
There is lots of info out on the internet, yet in the end, you are the judge. Keep smoking, and take notes. I take a lot of pics because pictures have a built in time stamp and I can add my notes later. Sometimes I'll snap a pic of my coal layout, and where I've placed chunks of wood. I'll snap a pic of smoke coming out the vent so I can look back and say I lit this at 9pm, and temp was 250F with clean smoke at 9.45pm. Good to know, even if the meat is going on at 10.30pm for an overnight cook.
And, keep posting here. The crew here has amazing collective skills for reviewing cooks, and sees things and asks great questions. I learn by reading what others are doing, and sometimes where others have had mis-steps.