i have been testing alot with Duty (the results have been inaccurate, read the whole thread: https://scsynth.org/t/sub-sample-accurate-granulation-with-random-periods/).
The only way is a phasor, where you derive a trigger from, which latches its own modulation in a single-sample feedback loop, to get linear ramps between 0 and 1 with random periods:
here my simple gen implementation, which works nicely:
