The mash schedules are set up to get a certain "profile". A mash at 149 degrees will give you a more fermentable wort, with a lower FG in the end. A mash at a higher temperature, like 156 degrees, will yield a less fermentable wort and a higher FG in the end. I'd mash a cream ale at 149, but I'd mash a sweet stout at 156.
That's just the mash schedule. You'll still sparge with your chosen method. That's just always assumed in a recipe. You'll want to sparge to get to your boil volume, with whatever temperature water you need to get your grainbed to 168. For me, when I batch sparge, my first round of sparge water is near 200 degrees because I'll drain my first runnings (say the mash is at 154) and then add half of the sparge water to get my grain bed up to 168. I stir like crazy, vorlauf, and drain. Then add the second round of sparge water, which is usually 170 degrees since my grainbed is already at 168. Stir well, vorlauf, and drain.