My question, How Commonly Used is the Bradford Factor?, was closed for being primarily opinion based (though I think it also got a few votes for being too broad). I can't seem to figure out what is too opinion-based or too broad about it. Although any question about common practice is somewhat opinion-based, there are a great number of questions asking if X is common practice that weren't closed.
There is a difference between "Is this common" and "How common is this".
"How common is this?" got the "too broad" closure votes because it's STILL too broad.
It could be very common in blue collar work, but not in white collar work, or in certain states, or certain nations, or even certain industries within certain states.
So, yes either opinion based, or too broad fits in this instance.
To elucidate a bit: (from comments) The first, "is this common", asks a simple question, which does not call for a quantifiable answer. you can answer "yes, it is" or "I see it all the time". The latter asks for a quantifiable answer: "It has found penetration in no less than 72% of the workplace". In the former, someone can answer "Yes, I've seen it occasionally" or "Never heard of it", in the latter, again, you're asking for something quantifiable.
We can not answer how common it is because how "common" something is is a bad subjective question. This is because common is a very relative term. If a major employer in the area uses the formula there is a good chance that other employers in the area emulate that because its already something that a good portion of the population understands.
I have edited the question to ask for specific examples of major companies that make use of the formula and how it is implemented in their policies. I think this will help get you the information you are looking for.