I went back and checked the brews I made during my first pass through the hobby. Surprisingly, very few were of greater than 1.056 gravity for most of that period. Most of the batches were in the 1.052 to 1.056 range. It finally dawned on me as to why they were in that range. I was using mostly domestic 2-row as my base malt and domestic 2-row comes in 50lb bags. Most the recipes were based on 10lbs of base malt and a pound of specialty malts, usually a half of a pound of torrified wheat and half of a pound of some kind of crystal/caramel malt. That brew house usually yielded 29PPG +/- 1PPG. I brewed 5.75-gallon batches, so that I could yield 5 gallons of clear beer to a keg. With an average extraction rate of 29PPG, that meant 11 * 0.029 / 5.75 + 1 = 1.0555. After I switched to using imported malt, I started using 11lbs of base malt per batch on average because imported malt comes in 55lb bags. That is when my range changed to 1.056 to 1.060. My desire to use a bag of base malt efficiently is what drove my O.G. range.