I have only ever applied to 2 jobs at once, where one was a definite fit and another was just to have an option. Except one single case, I've always gotten interviews and offers at both companies. We're out there, just weirdly lucky people. But also I know where to apply and where not to apply, and having a very narrowly tailored application/cover letter makes a huge difference in getting to the top of the pile (something I know from working with hiring departments).