I was assembling my new Delta tenoning jig (the first I've ever owned) and reading through the usage tips they offered a brilliant technique. I love precision. Maybe everyone else uses this technique but it was a revelation for me. I had always made home made jigs to cut my tenons and never happy with my precision.
The suggest to make the first cheek cut with a shim piece between the part and the jig. The shim thickness should be equal to the intended thickness of the tenon plus the saw blade width. So a 3/8" tenon with an 1/8" blade would be a 1/2" shim. Then make the second cheek cut by removing the shim piece leaving the part in the same orientation and you have an exact 3/8" thick tenon. Regardless of material thickness you end up with a tenon the exact thickness of shim minus the blade thickness. It is just up to the you to aling the first cut so you end up with a centered tenon.
Using an 1/* blade and 1/2 baltic birch ply for a shim one can get this exact thickness.
As long as you flip the piece end for end you will end up with aligned tenons even if they are slightly off center. Other methods could end up with a perfectly centered tenon but the width may very if the part thickness varies.
I really like this. Like I said maybe it is a duh moment for otthers but I was pleasantly