let me rephrase, i have my pile in the middle of the tank, and built it up , placing the smaller lighter pieces in a fashion to create a cave or tunnel along the back wall, i do not actually lean the pile and the weight agianst the back wall, so if the glass is good it should not be a problem now this does not mean it was a used or new tank, flaws (although there when purchased) can appear anytime in glass especially whith the stress we place on them, with all that water
now
this is a matter of preference(we all have them), some do some don't prefer this method, but the water has much more weight and pressure than the rock will, and although there is alot of debate on this issue, i know of tanks that have been this way for over 10 yrs, and one has 1200+lbs of rock layed out in the asme fahion(the tank is 715 gallons and can be viewed by all, online or at his store)