Think back to a recent session you played...
How often did you find yourself being led by a loose feeling when deciding on your preflop action (Whether or not to three-bet, call a three-bet, isolate a limper, or even raise first in)?
How often do you think, "I don't know, this feels right" before you make a preflop decision?
Every single time you think "I don't know" you just cost yourself some money.
There is an undeniable Law of Poker that states the more frequently you must make a specific decision, the more impact that decision will have on how much money you win or lose.
There is no strategic situation you will encounter more frequently than preflop!