It's not just incident numbers, when you get two slow drivers/semis blocking the lanes you have a large number(10+ cars) that tend to tailgate way under safe following distances. I've seen 5 cars all stacked together under one car length on many occasions.

All it takes is one stupid/wrong move and you have a massive pileup.

Most of the speeding accidents I've seen along I-5 tend to be single car unless they cross the divider.

Whenever I see it happen I usually double my following distance and let all the idiots sort it out but most people just tend to put themselves in a position where they don't have an exit if something goes wrong.