as you learn your craft, formulas can be very helpful in getting you started and allowing you to better understand the market.
but, just as with math, there is more than one formula out there.
each person that shares their secret formula with you is sharing what they have learned and what has worked for them. some of these things may work for you as well, and some may not. you will have to try different things to see what works for you.
by all means, read what has worked for different people, learn from those things, apply them to your own situation, but be willing to tweak them as you need to. 