Hi Mark,
Your follow piece is very helpful.
> " If I’m looking at a stack of resumes and have to quickly whittle them down I usually eliminate resumes where people switched too many times and didn’t have a single place that they stayed for 3+ years "
Is a lot more reasonable than the original title (when I see it with people), especially when applied to those ten or fifteen years into their current career (edit: originally I said "30+", but then I realized age is an illegal question and that there may be people who switched careers at a later age e.g., by going back to college for a CS degree at 25).
> Again, this is totally fine. I recommend to people that you put on your resume the reason that you changed jobs.
It would make sense to do this for 6 month stints, but not for 18-36 month ones. One reason is that this question is already asked on most employment applications. It can be confirmed through a reference check (I am still surprised when companies don't do this prior to making an offer). Having reasons stated all over the resume can be perceived as excuses and as bad mouthing (in public, given that the resume is read by many and may be publicly posted) former employers (e.g., if one put down "insufficient challenge" or "inadequate compensation").
When hiring engineers, resume screening should be done by engineers (or at worst, engineering PMs). I know they will hate it, but remind them that they will hate working with bozos a lot more.
I can find a lot better heuristics: do they just list keywords, are there obviously technically inaccurate things, are descriptions full of "wank words" vs. concrete, measurable, achievements. Asking candidates to submit an answer to a _simple_ randomly chosen question along with the resume (e.g., "in C what's wrong with this code: int* foo (void) { int n = 3; return &n; }", posting puzzles (like Facebook does) or doing a "fizz buzz" test over Etherpad are much simpler filters.
If there are red flags on the resume (and I agree that lack of 3+ year stays ten years after the person has graduated college is a red flag), the place to address them is either right before an in-person interview (after a phone screen) or right after (before making an offer). It's the role of the hiring manager, team technical lead and company HR to do this.
As an engineer conducting an interview or a phone screen, I already have a tough issue on my hand: give a binary answer after only forty five minutes with the person; time spent asking about their life's story (other than asking them about specific projects) is better spent finding information that will help me tell me whether they're technical and cultural (in terms of their ability to communicate, passion for software engineering/computer science, etc...) fit for the position or not.