5 gallon batch using new 10 gallon cooler

Today I used my new 10 gallon home depot cooler for a 5.5 gallon batch, it was nice having all that room but my effeciency dropped, I am usually around 77-85 %, this batch I was 72 % still not bad but!!! I tried doing some research on splitting the sparge water or just using the whole 5 gallons in one whack, although alot easier using all the sparge water at once I think it hurt my effiency, any thoughts? I usually did 3 rounds of sparging with the 5 gallon cooler setup, it was nice not to have to [FONT=Verdana, Arial, Helvetica, Sans-Serif]vorlauf 4 times today.
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Yeah I think not splitting could've hurt your efficiency. I was shown this technique over the weekend and I think its beneficial for batch spargers. Just split on the next one and see if you go back up...

Definitely need the multiple-rinse actions. Once that first batch gets saturated...it ain't gonna draw any more sugar.

Think of fresh water introduced to the grain bed as a freshly charged magnet...it has more capacity to saturate with the sugars that were left behind by the prior (saturated) batch of water.

As I figured, thanks for the replies, once I go to 10 gallons I'll have to split it anyways, but thats after christmas. Hey Biermuncher I made your oktoberfest ale today, I love oktoberfest and gave up trying to make an ale but saw your recipe and figured what the hell. I hope its good, after christmas I should have a temp controller too, so real lager, I love santa, she loves vienna lager and oktoberfest too. Thanks