Ok, I’m calling bullshit. There were 27 mass shooting events with >= 4 dead in the US in 2018:
https://en.m.wikipedia.org/wiki/List_of_mass_shootings_in_th...
(I used 4 dead as the cutoff, since it is close to the mean in the article’s data set.)
If you count people that managed to shoot at least 4 others, then there were 323 attempted serial murders, “resulting in 387 deaths and 1,283 injuries, for a total of 1,670 victims.”
The article may as well be titled “Serial murders can mow be performed in under an hour, thanks to improved technology”