For me, it really doesn't matter.... I can make trips all day long and be cost effective (wish I had that much scrap), simple because from the end of my driveway to the edge of the parking lot at the scrap yard is almost 1km on the nose... so I am less than 5 mins from my yard....

I have however considered building a small bailer for thin aluminum... things like vent caps, the flexable dryer hose, etc... the stuff that taked up too much room in storage....