Knapp Roofing interview questions

I ask general experience questions to the candidates about their experiences w/ the roofing system, construction in general, what kinds of tools they have & what they're familiar working with. Then I ask them how long they've been doing this kind of work & how many companies they've worked for. If they've worked for a lot of companies, that pops up a red flag to me b/c I wonder "why" they've worked for so many different companies. I've only worked for one company my whole career. If they've worked for a lot of companies, it makes me think they've been fired or lost their jobs multiple times. Then I usually call on 1 or 2 of the companies they've worked for & ask about them to get an overall prospective of them.