Low efficiency, Strike water volume problem?

I have been all grain brewing for almost 2 years now, and I never really paid that much attention to efficiency. The last few brews though have left me scratching my head. Low efficiency. At first my suspicion was that my grain was not being crushed fine enough, so I purchased my grain from the other LHBS, and the grain seemed to be crushed much finer. This did not seem to have a great effect on my efficiency.

I use a converted water cooler with a SS false bottom. I shoot for 153-4 degrees and never have a problem holding it. I always use two thermometers to insure that they are accurate. I add 5.2 to the mash, 60 min mash 6 gal batch. My last brew was 14 lbs of two row, .75 lbs carapils and 6 oz of biscuit malt. I also added .75 lb corn sugar to the boil and my OG was 1.060. Brew pal calculated to OG @ 1.072. I was wondering what effect strike water volume has on conversion? Brew pal has calculated my strike water needed as 5.7 gal. and sparge water at 4.5 gallons. That equals 1.52 quarts per pound of grist. this seems high, but could that effect my efficiency that much?

I've always shot for 1.5 quarts per pound. IMO 1 quart per pound makes too thick oatmeal consistency. You should be OK if you're hitting the 1.5 mark.

You might investigate the vigor by which you stir up your mash when sparging (I assume batch), because if you're not getting the sugars into solution your efficiency will be lower.

I usually make sure that the mash is stirred quite well, and make sure that I stir the mash several times during the mash. Im not sure what else could be my issue!