The Sky RC motor analyzer is also useful for approximating the point of diminishing return with timing adjustment. You can make a table whereby you do a Kv/RPM measurement at different timing settings within the motor's usable range. Looking at the range, it should be apparent where Kv and RPM are no longer rising at a beneficial rate against a timing adjustment. I found the new "short stack" motors I have like less timing (and consequently, show a lower unloaded amp draw), which I am guessing is because of lower resistance winding, while a couple of my older motors responded better to higher timing settings. It's by no means as useful as a loaded dyno, but it's better than simply "timing to temperature", and the difference is noticeable in how the car runs.