Hiring minima are the numbers of hours in various categories below which a company claims that it does not consider applications. When a company sets hiring minima, they are playing a bit of a numbers game to get the right pilots. What do they say you need? What does the insurance company say they need? What do they actually interview at? What do they hire at?
Sometimes customers, especially government customers, impose limitations on the hours requirements. Most Canadian provinces require 500 hours multi-engine experience for any pilot doing medivac operations. That's a government contract and is non-negotiable. If the company does a mix of medivac and non-medivac, and the chief pilot really likes you despite your only three hundred hours multi, they could schedule around you for a month or so, but that's unlikely. Kolinsky Air's major customer demands two-crew, two-engines, and a minimum of two thousand hours multi-engine time for both pilots. (No word on the Hooded Fang's transport needs).
Because of the theory that practice makes perfect, hours of experience is a measure of competence. When a company negotiates a contract with its insurance company, they may include hiring minima. Those can be bent and changed, because someone with the right personality who is a couple of hundred hours short will soon meet the minima, while two months of flying won't fix the attitude of the higher time guy who is a jerk. Therefore, don't be completely put off by insurance minima, but if there are plenty of good people who do meet the insurance minima, expect them to be hired instead.
Pilots will apply to jobs they are not quite qualified for, so companies need to advertise numbers high enough to keep out the riff-raff. I remember back when I had only a thousand hours, visiting Quoll, even though they demanded 1500 hours. I told the chief pilot straight out that I didn't meet his minima, but that I was interested in the company, so I would like to introduce myself. He picked up my resume and said, "This is what I'm looking for. I just put out those numbers to keep the 200-hour wonders away." (A commercial licence requires a minimum of 200 hours flight time, so a pilot who has just finished his initial training and thinks he's ready for anything is a two-hundred hour wonder). I probably would have landed a really nice job there, too. But someone flew some airliners into some buildings and for a while after that no one wanted to travel on airplanes anymore, and by the time Quoll Air recovered, I no longer had contacts there, and no longer had just the right number of hours to be useful to them.
How can one have too much time? Well if you've got significantly more than the minimum time at Bilby, you are approaching the minima at Gerbil, which pays better, flies nicer aircraft and has better bases. And the boss knows that if you're any good, there's a good chance you'll go to Gerbil or one of its ilk as soon as you meet those minima.
I can see another dynamic at play, especially near the top of the pyramid. Westjet demands 4000 hours total time. Air Canada is coy about minima, but definitely hires with less. Does that mean that Westjet gets better pilots than Air Canada? Well, no. Most pilots will apply to both airlines. By the time a resume has 4000 hours on it, it has probably been in Air Canada's system for a year or so. So the folks that get interviews at Westjet have either been passed over by Air Canada or never applied to Air Canada. The company cultures are different, but not so different that the majority of people who work out for one wouldn't have been good for the other. Westjet's minima have already dropped a fair amount. I'm betting they will come down again.
So with all the machinations that go into these numbers, when you see that the requirements for total time, pilot-in-command time, multi-engine time, multi-engine PIC time, time in a particular environment (e.g. mountain, coastal, northern, or complex airspace), and time on type all line up with your resume, it's like checking your lottery ticket against the winning numbers. The size of the jackpot then depends on how many people are holding the same numbers. Last time I got a good match right across, the chief pilot called the next day. Jackpot?