How many rounds of interviews is best?

As many as it takes to make an informed decision about the candidate's fit for the role… how is that for a non-answer?

But seriously, this is going to vary widely depending on the role, the need, the company and the candidate. There are so many variables that we can't be prescriptive here.

But for the vast majority of roles, when following the HireBest approach, you should be able to get the data you need to make a decision entirely within the decision round (hence the name!).

The screening round and first round are important though, so you don't waste time conducting extensive decision interviews with a candidate who doesn't meet the basic criteria for fit against the Cipher.

So, at a minimum: a screening round, followed by a decision round, possibly with a first round in between in some circumstances.

That said, don't skip an extra round if you need it to have confidence in your decision. The cost of a bad hire far outweighs the cost of a couple of extra hours up front.