Are you trying to adjust your mash pH 5.2 for all of your beers? If I am between 5.2 and 5.6 I feel I have done a good job and I am always in that range. My lighter ones come in at around 5.3-5.45 and my darker ones are down in the 5.2 range. I set my brewhouse efficiency for 80% for lighter beers and normally hit it within a point or two. The darker ones with more specialty grains are down around 73-75% (they are always in that range) and I just live with that. In addition, I am usually spot on to what Bru’n Water predicts for the specific water profile I am using.
If I can learn something new here to increase efficiency, I am all for it. BTW I only fly sparge and don’t do BIAB.