Organization and simply brewing on a regular basis is probably the single best thing you can do - the more familiar you are with your system and routine, the faster you are, and the better you can anticipate steps/
*Chiller is a MUST for a fast day.
*Having everything set up the night before - grain crushed, pots assembled and in the right area. Water ready to go, water additions figured out and ready to go.
*Get water heating early - right when you wake up if you plan on brewing first thing.
*My system allows me to start a second mash while I am boiling the first beer. As soon as I cool my first wort, get it in the fermenter and clean my boil kettle I am ready to sparge my second beer and start on boil#2.
*Take advantage of down time to clean up. During the last boil, I am cleaning out my Sparge water kettle and mash tun. During chilling, I am cleaning up all the odds and ends and my brew room. By the time my wort is done chilling, and is transferred to fermenter, the only thing I have left to do is clean my chiller and boil kettle and I am done.
If I am super organized and have grain ready, water ready, etc. I can knock out two 6.5 gallon all grain batches in under 6 hours - including cleanup.