How argo Improvement is in percent and not total numbers?

my english is bad I hope you will understand the bottom point of my post

in my case from 230ms to 140ms 38% total of 110ms
in this case from 952ms to 437ms 54% total of 515ms
in this case from 1108ms to 670ms 39% total of 438ms
in this case from 459ms to 157ms 65% total of 302ms
in this case from 651ms to 316ms 51% total of 335ms

my point is the final number of improvement should be the same for all website no matter how slow their origin is

because if for example waze find a faster route by 10 seconds, no matter how long your route is all they can do is save you 10 seconds, but in argo case for some reason the slower your origin is the faster route they find, why if my origin response in 1 second argo saved 500ms but other origin which response in 600ms argo saves them “only” 300ms

wouldn’t it be more logical if the total amount of improvement was pretty much the same in all cases no matter the speed of your origin?

if I would make an artificial slowness in my server so it will sleep for 1 second before responding would I still see same total amount of improvement(100ms) or somehow I would get again around 38% of improvement?