My first job, it was a big company and they required 3 professional reference. It just was a procedure. Being a first out-of-college job, I had to track down my HS summer job boss for it.
My latest job, they didn't do any reference check. They didn't even ask.
My GF works for PWC. Her company didn't even ask either because they don't 'trust' the obvious biased info. But they did their own extensive background check.