The escapement is "synchronous" in that the motion is controlled by the number of pulses applied to the motor over time rather than the duration/width of each pulse. The pulsetime constant is only to accommodate mechanical/analog differences with the driving circuitry, from what I understand. https://en.wikipedia.org/wiki/Lavet-type_stepping_motor
That's fascinating; the Lavet-type stepping motor acts as an escapement all on it's own by being a very simple stepper motor, so you don't end up needing a miniature version of a classic mechanical escapement, which is what I'd always imagined in my head when thinking about how cheap quartz wall clocks worked.
https://en.wikipedia.org/wiki/Escapement