So what happens when your kitchen is 65 degrees in January and your flour is cold from the garage? The back of the hand trick works when nothing changes, but home bakers deal with way more swings than some guy at a mill who does the same batch every single day. I check with a thermometer because it takes two seconds and saves me from a dough that proofs like a rock. If feel works for him, great, but "it worked twice" is not really proof of much.

Buy once cry once, man.

Tape measure with the numbers written on both sides. Sounds dumb but I stopped flipping it around and guessing. Small stuff adds up on a long day.