Something I often hear is that heavier lines on a given rod are useful for quicker loading/faster shots. I’ve never found this to be the case and experimented years back for quick snakehead shots. However I never actually made a video until now!
Perhaps not the most scientific experiment but it’s something you can also try at home. Of course there are other important considerations when it comes to fishing and the rule should always be choose you fly (size), choose your line weight, choose your rod. So rather than “underlining” a better concept might be “overrodding”!