I am happy since recently I improved my brewhouse efficiency as figured in ProMash by around 8 points, up to ~79% - 80% for 1.060 - 1.075 OG beers (still working out the variation by OG), by treating my sparge water as well as my mash water, per Bru'n Water v1.12. I used to only treat the mash water. Of course YMMV depending on your starting water. And I plan to test my pre-boil wort pH from now on too, to shoot for Martin's recommended 5.2 - 5.4 pH.
For a number of years I couldn't figure out why I was sticking at a lower efficiency than many other brewers, even though I had followed the recommended efficiency improvement practices of crushing til I'm scared, balancing runoff volumes of my mash and batch sparge runoffs, keeping my mash thickness to no thicker than 1.5 qts water per lb. of grist if possible, hitting a sparge temp of between 164F - 169F. I assume you know the drill.
Although my beer has been good until this improvement, the efficiency jump hasn't hurt beer quality, and the better efficiency lowers my cost per batch which means to me that it is important to improve processes that improve efficiency when those changes are just following new SOPs, if your system/schedule allows it.