Just about everything I've read says that it takes about an hour to sparge a 5 gal batch but mine only takes about 15 min if that. I have a rotating sparge arm that I made out of 1/2 inch copper tubing and I use a March pump to push the water through the arm. Even if I regulate the flow as slow as I can to just get the arm to barely move it's still a fairly quick process. Could it be that my laughter tun is just a good design that allows the wort to flow freely or am I likely leaving behind lots of fermentables? My efficiency seems like it could be a little better but I don't think it's too bad. If I'm brewing a recipe that says the target OG should be 1.054 I'll probably hit between 1.054 and 1.051. I know there are lots of thing that can result in poor effiency other than sparging techniques.