If the bag you put in the bag was emty it could use less space in another bag. But if the bag is full, it should take exactly the space that it has.

hope that makes sense.

how do you know 90 is the best setting for you if you cant tell what is 90 by looking at it?

I think its fine the way it is, because its not like somebody says 90 is the best and every little kid follows that. Instead just learn to make up your own stuff, and trust that. dayz too deep 4 you :D