You're drunk if you think any writer in the world calculates like this.
They don't, instead they either make clear statements or portray feats visually, but either way we (as readers) have to interpret both.
In my opinion it's our job (for those who are interested in it) to interpret and calculate feats and things if we want to have a good, comprehensive and cohesive understanding of the science that rules the One Piece world in order to see how it all works instead of just assuming that everything works exactly how we assume it does.
Maybe I'm wrong about everything, but that's okay because that's how we build a scientific model, by distinguishing what works from what doesn't.
I guess I'm a bit too obsessed by the need to grasp and understand everything, but that's just how things are.