I'm about to start my first AG batch today but I'm not sure how worried I need to be about multiple pre-boil gravity readings. I do not have a refractometer yet and don't really want to lose several tubes full of beer to take multiple readings, however, I don't know if that is a really bad idea or something I shouldn't worry about at this stage. I was planning to take one reading after the boil and then a FG reading after fermentation. Is this OK? My recipe is a Troegs Hop Back Amber Ale clone that I worked with my LHBS shop on to get the exact amounts of water to mash with and batch sparge with as well as the temps for my mash and sparge. I'm assuming if I hit those temps I shouldn't have to worry about efficiency, etc, right?