There are as many different interviewing techniques that would be successful as there are different types of software jobs. If you're hiring for people to churn out code 80%+ of the time, perhaps 80%+ of your interview / test process should be about that. However, we don't hire people to crank out code in a bubble - we hire people to work with others typically. This starts to tilt more important skills towards technical decision-making and ability to communicate effectively.
If all you're going to do in that dialogue is have a back and forth at a high level instead of looking at and writing some code, you're not going to be selecting well on a technical basis and you're really getting a randomized sampling of a distribution of technical skill of people that are applying for the job.
Yes, I think I can see the randomized sampling in my team almost :P
That is actually what prodded my question, because out of the colleagues we hired this year, half of them are amazing and half of them left because they couldn't keep up, so I wanted to know how to improve the "90 minute dialogue and go by your gut" interview process.
If all you're going to do in that dialogue is have a back and forth at a high level instead of looking at and writing some code, you're not going to be selecting well on a technical basis and you're really getting a randomized sampling of a distribution of technical skill of people that are applying for the job.