Earlier quoted context omitted.
"This information is very important." Years != Experience ...but thanks for confirming the shallowness of the recruiting processes we've all experienced.
that has nothing to do with shallowness, if someone has spent a few months at X previous jobs before you, this is definitely something to be addressed in the interview. Had an acquaintance recently that hired a guy that didn't pass the probation period at 2 out of 3 jobs he had. My acquaintance didn't address this at all and hired him anyway. In a few short he managed to transform in the whole office to a hard to bel…
Now are there reasons why you might ask someone how long they stayed at their previous job? Yes, definitely. Does that make everyone suspect automatically? Hell no.
I don't have more data on the subject, so I won't draw any definite conclusions as to whether it is warranted to base someone's professional worth on the number of years/months served. My own experience shows only a very weak correlation there, and no correlation at all between seniority within a company and said company's attempts at retaining that employee.
I've seen people who had "ten years' experience" who in reality had done the same year, ten times. I've seen people who had three years' experience but were driven, looked into things on their own initiative and who outclasses those "seniors". It all seems to depend on what you're exposed to and, lacking exposure, what you'll subject yourself to of your own accord.
Have you read any studies on the subject?