On average... over eons. Extinction events aren't like John Kerry or Slow-Joe Biden saying something stupid, occurring on a predictable schedule. A comet hits sometimes every 12,000 years, sometimes every 3.86521478 million years.
To get a sense of time... Stretch your arms out. This is represents the timeline of earth's ~4.5 billion-year history. The distance from your left fingertips to the wrist of your right hand represents the pre-Cambrian (pre-complex-life) period. All complex life on earth exists in the time represented by your right hand. And "in a single stroke with a medium-grained nail file you could eradicate human history."*
* John McPhee "Basin and Range" as contained in...
And, yes, I believe in God... and comets, and asteroids, and meteors.
Bryson's great but you really should read McPhee's entire 4-book Annals of a Former World series for a better understanding of Deep Time.
Or, if you like time lines. Envisage a time line reaching from the dinosaurs, in LA, to the present day, at Ground Zero in New York, this happened 6 block away or half a mile, not even across the Hudson river....
Consider that carefully.