I've observed across multiple meats and cuts of meats that the other impact of smoking varies greatly. Additionally, while actually smoking my perception of the flavor is overloaded and doesn't return to normal until probably the next day. The three variables I consider are the meat itself, the time spent in the smoker, and the temperature. Outside of extremes (like obviously too hot or too short) I find it virtually impossible to disentangle the individual variables' impact on desired outcomes (smoke flavor added, fat rendering, protein breakdown) and undesired outcomes (dry, tough, et cetera) The goal is to adjust my recipes more purposefully and efficiently; not just to follow someone else's recipe. Is there a proxy (not simply tasting) way to know the amount of smoke penetration or smokey flavor? Edit: I'm thinking something along the lines of the charts showing sous vide eggs by temperature, or the doneness of a steak, or milk in tea. The intent is to known that "it's done enough" while smoking. 
My BBQing colleagues use the cut-test - a ring of smoke penetration can be seen (in pork and chicken at least, I don't know about darker meats) in the meat that has some bearing on how heavily the meat has been smoked. I don't know if this is standard practice or just something they came up with (Edit: turns out it is something BBQ judges look for). It seems that this is related to how long the meat was smoked, how hot the smoker and probably how the meat was pre-treated (brined?, marinaded?, rubbed?). In response to @phil's comment, I have been to the source of all BBQ knowledge, amazingribs.com, where they combine science and BBQ and had a look for smoke rings: It turns out that the smoke ring is actually linked to Myoglobin - a pink protein in the meat, and its exposure to heat, nitric oxide and carbon monoxide, NOT smoke (particles in suspension in the air) per se, but gasses made by combustion of wood or charcoal in the presence of air. It only happens at temps below 170 F (~77 C). So it doesn't directly measure how much smoking has gone on, but rather how long it has been in the presence of CO and NO at relatively low temperatures - often in direct relation to how long it has been smoking. So - TLDR, the "smoke ring" is not directly related to smoke, but rather to the presence of gasses found in high abundance in smoke. 