ok, now that i grasp what youre trying to say, i believe that youre incorrect
i say this because i think the size of the object that kamui is being used against as well as the speed at which kamui is being used are both proportional to the amount of chakra thats used, and im judging that based off of how kakashi reacts after he used kamui in each instance
diedaras arm
diedaras clone explosion
ms susanoo arrow
bansho tennin nail
asura path missle
now if the chakra consumption for kamui was relatively constant rather than based off of the size of the object being kamui'd then kakashi would have died of chakra exhaustion by using the tech against pains bansho nail at the speed he had to use it , he already endured a lengthy fight with pain and used raikiri/variations several times but could still crank out 2 kamuis, even though when he fought diedara he used kamui twice and collapsed, that leads me to believe the size of what is being kamui'd along with the speed that the tech is used directly relates to how much chakra he must use to accomplish it