[Mezzie]

I don't know why you'd ever do an ambush interview for a developer position. Programming is very much a 'think and plan' type of activity.

Actually, I wonder if the prevalence has anything to do with the fact that an ambush interview style has certain advantages if you're hiring an HR person and therefore the people designing interview norms think it's a good idea?

(I can see this style having some utility for positions where the candidate has to deal with high-stakes social situations with very little prep, like HR or PR. "Prove your ability to calmly handle the unexpected and reorient.")