This is bad statistics. If your only evaluation of an employee is their resume or work history then you've already failed, regardless of what it is. You need to personally evaluate their work history. If you have knowledge of the work environments at different places then that might help you evaluate whether someone is truthful about their reasons for having short stints. If you don't then you'll have to use your judgment of their technical skill, interpersonal skills, etc. (all the stuff you get from the in person interview) to make that determination.
Ultimately, the resume is a very weak form of recommendation for or against any particular individual, in my opinion. I've seen people with very strong resumes who couldn't code their way out of a paper bag. I've seen people with patchy or "weird" resumes, no CS degree, sometimes no college degree whatsoever who were top tier developers worth their weight in gold. Your screening and interview process needs to be good enough to be able to provide a reasonably trustworthy result even without a resume, if it's not then it's a failure. If it is, then it's comparably easy to make a decision on someone with lots of short stints.
Also, I find this whole discussion a bit odd in a couple ways. For a lot of big companies (like Amazon and Google) the average tenure is only about 1 year, and people here are drawing attention to 1 year as some sort of red flag duration, when in reality it's super common for a lot of devs at a lot of companies. Another is that I don't see people being concerned about overly long periods of employment at the same place. To me that's potentially a red flag too because it might indicate someone doesn't have the sort of job prospects necessary to get hired elsewhere. Though, again, you do need to always rely first and foremost on the in person interview.
Someone's resume might raise questions but it's unprofessional to fill those questions in with prejudices, you need to answer those questions with data from phone screens, homework assignments, in person interviews, etc.
Ultimately, the resume is a very weak form of recommendation for or against any particular individual, in my opinion. I've seen people with very strong resumes who couldn't code their way out of a paper bag. I've seen people with patchy or "weird" resumes, no CS degree, sometimes no college degree whatsoever who were top tier developers worth their weight in gold. Your screening and interview process needs to be good enough to be able to provide a reasonably trustworthy result even without a resume, if it's not then it's a failure. If it is, then it's comparably easy to make a decision on someone with lots of short stints.
Also, I find this whole discussion a bit odd in a couple ways. For a lot of big companies (like Amazon and Google) the average tenure is only about 1 year, and people here are drawing attention to 1 year as some sort of red flag duration, when in reality it's super common for a lot of devs at a lot of companies. Another is that I don't see people being concerned about overly long periods of employment at the same place. To me that's potentially a red flag too because it might indicate someone doesn't have the sort of job prospects necessary to get hired elsewhere. Though, again, you do need to always rely first and foremost on the in person interview.
Someone's resume might raise questions but it's unprofessional to fill those questions in with prejudices, you need to answer those questions with data from phone screens, homework assignments, in person interviews, etc.