As @lewm points out, lots of variables. But at least one measurement isn't hard: Analogue Productions test record 1 KHz tone, running into a frequency counter.
Control condition: with platter up to speed, disconnect motor and measure the time required to run down from 1000 Hz to about 900 Hz with stylus engaged for 1 second out of every 10 seconds, giving a good approximation to '90% stylus not engaged').
Experimental condition: time to same frequency drop with stylus fully engaged.
In this way differentiate bearing friction from stylus friction. Easier for me, as my air bearing is virtually frictionless.
Control condition: with platter up to speed, disconnect motor and measure the time required to run down from 1000 Hz to about 900 Hz with stylus engaged for 1 second out of every 10 seconds, giving a good approximation to '90% stylus not engaged').
Experimental condition: time to same frequency drop with stylus fully engaged.
In this way differentiate bearing friction from stylus friction. Easier for me, as my air bearing is virtually frictionless.