Four-times major champion Koepka took a two-shot lead into the final round of the Masters but closed with a disappointing 75 to finish in a share of second place and left to wonder what went wrong.
"I didn't sleep (that) Sunday night just trying to figure out what exactly it was. Thought about it for a few days after and really honed in on what I was doing and what went wrong," Koepka told reporters at Oak Hill on Wednesday.
"From there just never let it happen again. That's the whole goal, right? You're not trying to dwell on it.
"Yeah, it sucks to finish second, but at the same time, as long as you learn from it, you'll be fine."
When asked to share what he learned from his latest Masters appearance Koepka said he preferred to keep it to himself.
Koepka, who won consecutive U.S. Open titles in 2017-18 and went back-to-back at the PGA Championship in 2018-19, is one of 18 LIV Golf members in the starting field this week and perhaps the most confident of the bunch.
Starting with his 2017 U.S. Open win at Erin Hills, Koepka has finished either first or second in eight of the last 21 majors in which he has competed.
Prior to the 2019 PGA Championship Koepka said the majors are sometimes the easiest to win and shared his own algorithm that essentially reduced the field to about 12 players he needed to beat. On Wednesday, Koepka said his formula still holds true.
"I still think it is, yeah. I still think there's a lot of good players, and they should think the exact same thing. You should have a lot of confidence," said Koepka.
"When you look at the major leaderboards over the last, I don't know, maybe five, six years, I mean, it's pretty repetitive on the guys who are at the top. So I think it's still the same."
Oak Hill has undergone an extensive restoration since it last hosted a PGA Championship in 2013 and its narrow fairways, deep rough and steep-faced bunkers will provide a stern test.
Koepka, who will play the opening two rounds with world number two Scottie Scheffler and 2019 U.S. Open winner Gary Woodland, said patience will be critical.
"Every time I've won, I've been super disciplined; where I hit it, the shots, not doing exactly maybe what - I might want to hit driver off the tee, but it's not what the hole or pin location calls for," said Koepka.
"Just staying patient. I think that's a massive thing to win a major."