Jason Fried argues you should disqualify 75% of leads early instead of wasting resources on low-fit prospects. Spending 10% of annual revenue to persuade unqualified people who'll never buy or drop out later is the real waste.
It should be disqualifying 75% of the population out there and then leaving you with a quarter of qualified leads who are ready, willing and able. Instead of me trying to convince all 100 of them and expending my marketing resources, expending my 10% of my annual revenue of my marketing budget, instead of expending all that budget on 100 leads, 75 of them which are going to disqualify themselves later in the process, or I'm going to chase them around for the next 12 months, they're never going to buy for me. I would rather disqualify 75% of them and be left with 25 rock solid good leads.