thats how i'd read it. but the water temps seem a bit high to me if you're shooting for 155 mash and 165 mashout temp

 

You can always run your numbers using the Mash Calculator on this site. You need the weight of grain, the temperature of the grain and the mash thickness. Assuming you're near sea level (I'm not!), you don't need to adjust the water's boiling point. When I run the calculator using 10# of grain, 4.5 gallon mash-in, I get a strike temperature of 165 degrees, not the 175 you mention. If you're using 20 pounds of grain, I get 175 degrees for the mash-in temp. Using those parameters, for your mash-out I get 7.9 qt at boiling (212 degrees F). It takes me 11 quarts at 200 degrees boiling point (6000' elevation) to get the same mash-out temperature.

 

+1 for the Mash Calculator.
I'd never trust numbers for mash schedule in a recipe. Mash temps, yes, but water additions and temps not so much. First off you have to be certain that your tun will hold the grain and total water (including strike, additional rests and mashout). There's a handy calculator for that here... http://www.rackers.org/calcs.shtml called "Can I Mash it" that will tell you the total tun volume you need.
From there you can determine whether you want to adjust starting mash thickness to enhance certain characteristics in the beer. Even if you brew exactly as the recipe is laid out, you can eventually use the calculator to make tweaks and changes that will fit your system and preferences.

 

The recipe,process and temperatures all reflect what happens in his/her brewing set up.
Each set up will give you different result.
As you brew more often and take notes on your particular efficiency, heat and wort losses, you'll be able to modify others recipes to work out on your system.
You can certainly use the recipe and process as stated, but I'd be ready with additional hot and cold water to adjust the mash temperature as needed.
Have some fun and take good notes.
Guess what? You're going to make Beer!
Cheers,
Brian

 

Yep, worst case you end up with something with which to drown your sorrows.... ;-) It's all trial and error, a degree or two off doesn't make that much of a difference at our scale and repeatability requirements.... RDWHAHB!

 

I know I rave on about brewlosopher but he tested mash temp and if tasters could perceive any differences between two beers one mashed low on the scale and the other high. The majority of the test tasters couldn't detect any differences in the resultant beers. Just my 2c but a grew degrees either way mightn't make a huge difference.

 

At our scale, mash temperature we read and record are generally guidelines - there's a lot of temperature variation within the tun (don't believe me: Take a temperature reading at the edge of the mash and in the middle). So we may have a 156 degree mash in the middle and a 150 degree mash on the edges. At a commercial scale, the mash temperature is much more consistent so any difference created through temperature control wouldn't get lost in the noise, which is what happens at our scale. If you're doing some kind of temperature controlled mash, all bets are off but for us cooler-and-false-bottom guys, we just can't control temperature closely enough to notice a difference.