How do you go about testing your wine, when you have 12-5gal carboys and a barrel?
All at once, break it down into lots over days or just random?
Goes for SO2, PH and TA.
I've never really found the need to test all at the same time, prefermentation I don't sulfite, so that's zero, but do pH/TA before AF and adjust as needed. Post AF and MLF, my SO2 is zero(ish), so I test TA and pH at the same time, one wine at a time. Take a 5 ml sample, shake to degas if needed, take a pH reading, add 10 ml DI water and perform the titration to get TA, record the findings and move to the next wine.
I don't make adjustments until I have taken all of the readings I intend to do, as it seems easier for me to go into pH/TA test mode, get it all done and put most of that stuff away, and then go into calculating and making adjustments mode.
As for SO2, post AF and MLF, during barrel and bulk aging, I follow the 1/4 tsp / 6 gallon rule until it's time to bottle, at which time I take an SO2 reading and add sulfite based upon my final pH.
Just my way.......