I track feeding schedules including offerings, successful feedings, refusals and regurges.
I track weight prior to each feeding with juveniles up until they have reached approx full-size, then I weigh roughly monthly. Length I track roughly monthly until approx. full-size is reached.
I also track sheds including when they turn opaque, when they clear and when they actually shed, along with any notes.
I don't track each defecation, but I will make notes if any of my snakes "bathroom pattern" seems a bit different from usual.
Some info I track for my own educational purposes, some I track in case there are any issues. If any of my snakes need a vet trip I will be able to answer their questions accurately and help them to provide the best medical care they can.