In my limited experience with pH meters and Bru'n Water; the software I use to calculate estimated mash and needed adjustments, I see no point in buying meter or strips with an resolution of less than +/-0.05.
The algorithm in Bru'n water is within this level of accuracy with my brews thus far. I have a meter with an accuracy of +/-0.01 (Hach Pro+).
I calibrate it for each brew day and measured pH is usually within 0.05 of my target. (still in the learning phase and making adjustments to predicted mash acidifications as my data set grows). The last brew was off by 0.02 of target mash pH.
Two good tools being used; the software and meter. The good folks shepherding things in the brew Science forum have been enormously helpful. Still a lot to learn but feel competent to involve myself in such discussions as this one. Perhaps I am blissfully unaware of my ignorance and this last statement is a joke to many readers.
The meter and needed solutions were about $200. Not sure exactly but I view it as money well spent.
Hach Pro +View attachment 279726
A calibration solution in useView attachment 279727