For one thing this is a good reminder about how forgiving beer can be. We can get lost in brewing chemistry, mash temps etc. but you can put together a perfectly good beer without much planning if you have the basics down. While I have not done a 15 minute mash and boil, a lot of my brew days are similar to the one Marshall describes: I realize I have a little bit of time, I see what I have for ingredients, figure out water volumes on the back of an envelope, grind grain into a bag while a kettle of water with a teaspoon of gypsum comes up to temp and go. I don't know if my very best beers were made this way but never any bad ones.