I have measured the area I spoke about, I at one time surveyed for a living, so measuring and calculating was something I was forced to be very accurate with in my job. I measured every distance with a electronic distance meter (which had the accuracy of + or - .02 of one foot) when laying out my pads and buildings to grow chickens. I have one area that is 50' wide and 500' long, another area 100' x 500', another 75' x 500', and another 35' x 500'. This equates to .57 ac + 1.15 ac + .86 ac + .40 ac, which comes up to a total mowed area of 2.98 ac in between and around my chicken houses. I mowed this area while trimming around 3-1000 gallon propane tanks...3-10' x 25' concrete feed bin pads...1-10' x 12' generator building...1-10' x 20' concrete incinerator pad...2-power poles...and 2-guy wires. I basically mow a straight line distance for 500', turn around and mow the same distance back. This is about as easy as it gets, and I mowed the entire area plus trimming in a timed 43 mins. I mow grass at full speed with a Hustler Super Z for probably 50% of the time I'm on the mower, don't believe you can't mow grass at 13 mph, I do it all the time, and have actually had people such as yourself come and run my mowers because they did not believe it either, but when they finished, they had become a believer. I hardly ever slow down into the 8 to 10 mph range, unless it is extremely rough, of which I have very little that is really that rough, but some yes.