Portrush - World No 1 5 contenders for the Open Championship
Koepka's record in golf's big four tournaments is made even more remarkable by the fact he has won only two other regular PGA Tour events, the Phoenix Open in 2015 and the CJ Cup in South Korea last year.
But Koepka says there is a perfectly simple explanation to his success.
"I just practise before the majors. Regular tournaments I don't practise," he said.
"If you've seen me on TV, that's when I play golf... On Wednesday was the first time I touched a club in, what, ten days. That happens week in and week out. And majors I like to play the week before and find a rhythm, build a rhythm."
Koepka has often been left bewildered by a perceived lack of media interest in his achievements, and he questioned why he barely featured in an advert for the US Open earlier this year despite being the two-time defending champion.
But he now says despite keeping his "chip on the shoulder", he is just focusing on adding to his already impressive major tally.
"Like I said, over the last year and a half, I just felt like if other guys had done what I had done it would be a bigger deal.
"Now it doesn't matter to me. I've got my own chip on my shoulder for what I'm trying to accomplish."