I'm a HM at a big tech company as well. We do 3 one hour slots.
In a previous company we pair interviewed, 1/2 hour screen + 2 one hour slots. I liked that format a little bit better.
I've been interviewing people for about 40 years now, I was just reflecting on my first ever interview that I participated in when I was still a teenager.
I would say there are some factors that are not going to come out in any number of interviews. Conversely there are factors that are immediately noticeable.
I can tell in 10-15 minutes how strong someone is technically. At least I can tell the difference between "weak", "maybe", "strong" in 10 minutes.
Going back to my first ever interview. The guy was brilliant. He was technically good. He ended up being a not so good hire for reasons that would have been very hard to discover during the interview. It was partly the intersection of very smart without the experience to match and partly that he was just weird in some other ways. He was hired, he left within a year or so.
I think the science says the best predictor is an IQ test. The rest of our practices are not really evidence based. We tend to want to hire people that are like us, that know the things we know, we have all sorts of biases during the interview process, and throwing more people/time at it doesn't really seem to make a big difference.
I would say the most important thing you can do to get good people is to make your company a place that good people want to be. I.e. what matters is more what enters the pipeline then the interview process. I would bet that having 7 interviews vs. 3 has a difference that's completely in the noise and that at least there's no solid evidence that it gets you anything re: the quality of people working in a company. Every company says it has the best people. Mostly channeling Joel Spolsky here but I've seen this principle in action.
EDIT: Another random thought is that there are other factors that influence whether someone is going to be successful in a given role. Even the best software engineer can fail if the conditions for him to be successful aren't there.
In a previous company we pair interviewed, 1/2 hour screen + 2 one hour slots. I liked that format a little bit better.
I've been interviewing people for about 40 years now, I was just reflecting on my first ever interview that I participated in when I was still a teenager.
I would say there are some factors that are not going to come out in any number of interviews. Conversely there are factors that are immediately noticeable.
I can tell in 10-15 minutes how strong someone is technically. At least I can tell the difference between "weak", "maybe", "strong" in 10 minutes.
Going back to my first ever interview. The guy was brilliant. He was technically good. He ended up being a not so good hire for reasons that would have been very hard to discover during the interview. It was partly the intersection of very smart without the experience to match and partly that he was just weird in some other ways. He was hired, he left within a year or so.
I think the science says the best predictor is an IQ test. The rest of our practices are not really evidence based. We tend to want to hire people that are like us, that know the things we know, we have all sorts of biases during the interview process, and throwing more people/time at it doesn't really seem to make a big difference.
I would say the most important thing you can do to get good people is to make your company a place that good people want to be. I.e. what matters is more what enters the pipeline then the interview process. I would bet that having 7 interviews vs. 3 has a difference that's completely in the noise and that at least there's no solid evidence that it gets you anything re: the quality of people working in a company. Every company says it has the best people. Mostly channeling Joel Spolsky here but I've seen this principle in action.
EDIT: Another random thought is that there are other factors that influence whether someone is going to be successful in a given role. Even the best software engineer can fail if the conditions for him to be successful aren't there.