I suppose I'll add my input since more have chimed in than I had expected. It has been interesting and insightful to read the responses. Thanks, all.
I've found no reason to chuck a stem if I run into one, unless it's as Tate posted above (thanks for that, I forgot to catch a pic for my OP!). Small veins and such always get packed and smoked. I find these littered in especially flake tobaccos, along with most C&D produced ribbon cuts.
I over-dried the bowl of GLP Spark Plug mentioned in the OP, and snapped up the stem(s) into pieces; then packing and smoking them in the bowl. I honestly have no idea if it added anything to the smoke (flavor or strength). I believe a more deliberate approach to catching any sort of data is to be cataloged before understanding just what it might add, though finding a stem is quite rare in-and-of-itself to be able to repeat with certainty of its affect.
Looks like if I find myself too impatient to dry a larger cut stem to be broken down and packed, I'll keep it at the forefront to chew it for a lil pre-nic kick, instead of binning it. Not sure I'd want to smoke a bowl full of stems, but I'd appreciate any sacrificial reports; of course, for science
.