you're never sure you isolated the empty slot, so you assume so, go deeper, then backtrack when you reached the leaf of that exploration tree. Also, the double scan thing made it quick enough to avoid trying to probe too long for the right slot, hence the hybrid solution.
On average it would take around 500 guesses. One would have expected that with your "method" you could have reduced this by an order of magnitude (i.e. not 800) at least. Otherwise you're really just wasting time with additional steps for each trial.
- mechanism is rusty
- has backlash/play
you're never sure you isolated the empty slot, so you assume so, go deeper, then backtrack when you reached the leaf of that exploration tree. Also, the double scan thing made it quick enough to avoid trying to probe too long for the right slot, hence the hybrid solution.