Not looking at Previously Interviewed!!
I know Hiring Managers (HM) have certain predisposition about certain type of candidates, In this case I am talking about people who were previously interviewed. In some cases these stances are so intense that if they or someone else in the company interviewed someone and said no for any reason, they will not interview them again even if 10+ years have gone by.
However this practice is not correct. A blanket stance of no to previously interviewed candidates is only hurting the company.
The reality is if a candidate was interviewed say 2+ years ago and was not hired due to lack of experience it is highly probable that 2+ years later they might have the needed experience, or a candidate who 2+ years ago was not hired due to cultural fit, may now 2+ years later be a fit. In other words find out the who, what, when, how and why of the reason for not hiring and then see if those reasons are still valid. In a lot of cases you will find they are not. Add to that, the fact that sometimes people say no to hiring someone for reason that are personnel, or even to protect their own jobs. It is ugly but it happens, a lot more than you would think. So just because someone was interviewed and not hired does not mean you should never look at them again. It just means you need to find out the reasoning and then take the 5-30 minutes on the phone to see if those reason still exist, and find out for yourself, not just take what the notes form 2+ years ago say. The same can be said of previous employees as well, find out for yourself. Sometimes it can lead to a great hire.