Lightning does strike twice (and more) in the same place
The diagram shows that lightning has repeated flashes at rates of 8 and 15 times per second. The interval 1/8 of a second is the time for electromagnetic waves to pass around the earth once and return to the starting point. Oscillations of 8 per second due to this fact where first theorised and then detected by Schumann and so it is called the Schumann resonance.
Although it is not an accepted idea, I think that this frequency of oscillation is instrumental in causing the development of life forms (such as human) with brain wave frequencies of a similar rate.
Once we have this connection then we can understand why there are more accidents when lower frequency waves are present and why people's reaction times are faster or slower according to electromagnetic fields that oscillate slightly faster or slower than the Schumann resonance.