If it was me, I would add 4 grams of baking soda to the mash water, mash, take a late mash pH sample (60 min.) or two (30 and 60 min.), carefully measure their room temperature pH after calibrating my pH meter, and take notes for the next time this recipe is repeated. Calibrate the meter, gently swirl the meter in the room temperature samples, then let it sit still in the sample for up to a few minutes until you see no further movement (generally upward in my experience) of the pH, and call this the stable mash pH for your sample.
I not only think that most people take their sample pH's too early, but that they are often rather in a hurry and thereby impatiently read them at temperatures somewhat hotter than they should, or they are at this juncture particularly nervous or agitated, and they therefore want to get a fast pH reading, thereby either reading while swirling, or forgetting to let the pH meter probe sit undisturbed for a few minutes in the sample to allow the reading to fully stabilize. All of these bad practices will lead to lower than actual pH readings. All of them are more likely than not the norm.
Many even make the quite egregious mistake of presuming that since their meter has automatic temperature correction, waiting for a 68 degree F. sample is completely unnecessary. Yet another false low pH reading.
Some calibrate hours to days (or more) before reading their samples pH. Calibrating a few hours in advance "might" work for the best of the available pH meters, but it will not work (as in retain its calibration stability) for most economy driven pH meters. No way will any pH meter hold a precise, reliable, and trustworthy calibration over a period of a few to many days.
Many have massive cases of mash pH assistant software induced "confirmation bias", and when they see the highly biased pH of their pre-choosing (via the software) magically appear (or even if they don't see it appear), that "snapshot" instantly satisfies them and gets recorded, whether too hot, or swirling, or uncalibrated, or unstable, simply made up, etc... Often this is powerful bias induced by a feeling that the software is somehow mystically or magically far superior to what their pH meter would honestly tell them if they did things correctly and accepted its honest output. This due to internet brainwashing by repeatedly hearing over and over again that the software being used is incapable of error.
All of this makes it quite suspect when trying to seriously believe that average Joe or Jane actually took a competently valid pH reading. All he/she reports on the internet for our consumption is some mystical achieved mash pH number (which quite often magically matches quite well with a software prediction). No indication at all as to the "honest" confidence of its validity (generally due to having no clue as to what constitutes confident and/or competent honest validity).
