In the interests of science, I carried out a study on how long it took for my games to be decisive. I took as my dataset all the even 19x19 games I played since the proper OGS winrate graphs arrived in December, which is 34 (pretty low .__.)
Then I took as my condition of decisiveness either 1. resignation or 2. one of the players achieves 99% winrate from OGS Leela.
These are the percentages of my games which were decisive within 100 moves:
Against DDKs: 100%
Against SDKs: exactly two-thirds (67%)
Against dans: 100%
The mean average move at which my games were decisive was 76.