I think we've gone through our house and made it more 'efficient' like 100 times. Yet again, we went through our storage room (which was to the point that you could not walk into it or see ANY floor) to a place where we can actually use it. The boxes on the left are all just that - empty boxes (so if/when we move, we have boxes for everything as you actually have to buy boxes here if you want cardboard). We can actually open the storage dresser drawers, and eventually I will make a storage rack for the boxes and stuff on the left of the ladder.
Our center room upstairs (that is in the middle of all the bedrooms and actually a huge waste of space because anything large there would block the doors) now has a small sitting area and lots of floor (before this was completely filled with stuff.
We've decided that if we need to make more space, we'll have to build a storage loft over the stairs for all the boxes... but don't think that would need to happen unless we end up staying in this house for a few more years.