I myself almost never worry or think about cadence. I just pedal at what ever speed feels right at the time.

I used to have an old digital watch attached to my barstem, and I did track my cadence once in a while by just using the stopwatch function to track my crank RPMs for 30 seconds; it was usually about 70-75 rpms. Best use of the stopwatch was to time myself during intervals on a local MUP or longer sections of stop sign and traffic light-free streets .