Though if I make a stack of boxes the same size the 80th box will be a smaller proportion of the whole stack as is than the 4th box was, yet the individual boxes feel the same size.
Edit: In saying that, if I was looking up at a stack of 80 boxes and someone added another on top it might feel subjectively like the tower was extended by less of an amount than if it was the 3rd box being added.
Our brains typically do judge based on relative change even when it doesn't make a lot of sense - I.e. we'll put more effort trying to save ~$1 on something less than $10 than trying to save $2 or $3 on something that's $100, or $10 on something that's over $1000. The former "feels" like a more significant saving - but a $1 is $1 either way. You can post-rationalise it by saying "but I buy $10 things more often than I do $1000 things", but do you really do 100 times as often?
Edit: In saying that, if I was looking up at a stack of 80 boxes and someone added another on top it might feel subjectively like the tower was extended by less of an amount than if it was the 3rd box being added.