I think one of the core aspects of a personal parser that doesn't get talked much about is the motivation it can bring. There can be times in dungeon or facerolling boring content that I literally just try to see how far I can push it. Capitalize on that feeling even more in a raid environment and it can increase your focus and determination (not the game stat, YOUR actual determination as a player).

One of the major things I've personally used a parse for was checking out different melding and testing the direct hit meta for tanks. Interestingly enough my war saw a higher gain with skillspeed and determination melds on my current gear but dark knight didn't see the same gains so I switched back to direct hit. The only reasonable explanation I could think of for it was Wars Berserk increasing attack power and the extra skillspeed and determination made auto attacks and gcds that much stronger during its duration. It was arguably alot better as long as there isn't much lucky fel cleave direct hits popping (Directly increase damage vs RNGing extra damage). A PS4 player is unable to do any kind of meld testing at all and left to follow metas and others advice.