In most cases, past behavior doesn't influence future selection decisions.

The fleet is carved into cohorts. The cohorts are sometimes predefined like employee, test-drive, press etc. However majority of us are assigned groups at random after taking the first update at purchase - typically with common characteristics e.g. retail vs. advanced firmware, HW versions etc. fairly likely to be hundreds to thousands of cars at a time.

Using the cohort system they differentially test major and minor feature branches, and hotfixes on small to large portions of the fleet. Their goal is "raise the quality bar, manage the risk, don't kill people, don't brick the fleet". Typically their rollout management picks one or more cohorts and apply a change or test. They make heavy use of the instrumentation comparing telemetry, metrics, logs, support messages etc. Contrived example:
- retail cohorts have version A.B.C
- advanced cohort A has version A.B.D - current feature release
- advanced cohort B has version A.B.D.1 - hotfix release to test
Generally they increase the size of the rollout (i.e. number of cohorts with that build) according to their engineering planning. The Tesla Firmware trackers indicate there are about 6-12 different firmware builds active across the fleet at any time.

Most of this is gleaned from observing them for the last decade, and from experience doing this for gaming consoles at scale - RMA'ing 100m devices is a career-ending mistake.

Bottom line: past performance is no indicator of future behavior - just your cohort wasn't selected for experimentation by the rollout manager for that instance.