One printing expert suggested using teh whole sheet, but not making stright exposure strip across it. Instead, pick a corner and work away, letting an inch more expose on the longitude and lattitude. This allows you too see the affect of the exposure across more of your frame. As you get more accustomed to this, you will be able to pick the corner piont taht will show you a combination of the more challenging areas of the print (i.e. face and sky, or something like that).