Here is a Wired article on how Microsoft tested the game Halo 3 on 600 game players playing over 3000 times. Microsoft watched each interction, and documented each move in each game. Microsoft knows to the square foot where each player died in the game.
Why is this method useful for you if you’re not in the game space?
Because it works.
Because it’s methodical.
Because you can rely on it.
Because you’re constantly improving and questioning.
Because you get to know your customer better.
Because you’ll trust yourself more after you go through this prep.
Because your customers will trust you more after you go through this prep.