Guide for how to accurately determine percent increase in volume for bulk fermentation

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Greetings.  Long time baker, but first time on this forum (from Bucks County PA). I've picked up a lot of useful information and perspectives here and I figure it's time to give back.  I saw a post awhile back in which a newer baker asked how to determine when their bread has risen by a given percentage during bulk fermentation.  Anyone who's watched dough rise in a wide bowl knows that it's really guesswork if done by eye. Below is Google Drive link to a PDF I created showing how to do it simply and accurately every time.

To forestall a post saying I could just use a dough bucket with volume markings, I prefer a ceramic bowl because it's much easier to do coil folds, and it releases the dough far easier compared to a plastic bucket (without breaking the skin on the upper surface).  I do, however, use a dough bucket for my initial mix until bulk fermentation starts, at which point I transfer to my bowl.

Art

https://drive.google.com/file/d/1UNIL_58VgTyClE-qe1MVYUY04iM3eQQj/view?usp=sharing