[absrec]

And have less rounds. I don't really understand why companies have multiple interview rounds. One of my friends recently gave three 1 hour rounds all technical.

If you're afraid of making the wrong decision then if one person makes 1/5 bad hiring decisions then 3 people make 3/5 bad hiring decisions not 1/125.

[mjr00]

These systems are made to optimize not making bad hires, not necessarily missing out on good hires. Given that, multiple rounds does help. Per your example, if each interviewer has a 1/5 chance of mistakenly approving a bad hire, then three interviewers does in fact reduce that to a 1/125 chance of the company making a bad hire.