In this instance we're talking about a dash action, typically 30 feet worth of movement for a PC. That's 10 yards. 1/4 of the 40-yard distance Offensive Linemen (!) in the NFL run in 5 seconds.
Sure, in a straight line, but 5 seconds to cover 4 times the distance (and they cover those first 10 yards in 2 seconds or less)
Honestly, it wouldn't even be that hard to proof of concept. Imagine Jerome Bettis with a greatsword on an inside run play, blade first.
Like, we're totally in 'a difference of taste' territory here, but I don't think some of these things are as far from normal human capabilities as you are suggesting.
To be clear, there’s a huge difference between a lunge by a RW highly skilled swordsman making a couple of attack lunges and being able to attack
everyone in a 706 square foot area (a 15’ radius circle) in 6 seconds. That’s almost 50% bigger than my entire apartment in law school, and about 80% bigger than the house I was brought to the day I was born. That doesn’t sound mundane to me.
I’m a LOT more comfortable with a 10’ radius area (approximately 315’ square feet).
Edit: and this is assenting that human capabilities are an appropriate baseline when most of the races in the game aren't even human.
I have been noting through several posts that what is mundane may differ based on species abilities.
Spelling it out and going back to my first post’s methodology of being system agnostic:
If a character’s base speed is based on his species (not class), then a high level mundane fighter’s speed might max out at 2 times* normal for his species. (The 3.X monks did something like this by simply adding 10’ base speed every few levels.)
That “heroic max” could be applied to a variety of metrics & mechanics.
If a normal human hold their breath for a number of rounds = 2x their Con bonus (or whatever), the high-level mundane warrior could hold their breath for 4x their Con bonus. But a high-level mundane warrior of a species that could already do 4x would be able to hold their breath 8x their Con.
See also things like max encumbrance, bonuses to saves regarding endurance, bonuses to resisting harmful magic, and so on.
* or maybe even 3 or 4 times. The exact number doesn’t really matter for this discussion, and if used, would need to be determined by playtesting.