In real life no one is fool enough to do such mistake nor anyone have time to do the stupidity.
From academic point of view, you need to do more study on it.
Kindly, learn design of structure.
Make simple plan.
Do calculation using fe415
Then
Fe 500
Fe 600
You may do calculation for study with
Fe 1000
Fe 2000 etc
Then compare all results and arrive at how much steel got reduced.
Then again do another studies for different type structures with floor variation.
Once you get all data, do share with us so that we too have idea on academic interest as i m sure enough that i m not the fool and will never ever commit such stupid think on my own, as i know its a design and not a halwa to categories the quantity base on test.