Grams are a lot more accurate in many cases. For something like a big python or BCC, grams don't make that much sense. But at ~28 grams per ounce, measuring my 8 gram house snake in ounces wouldn't make much sense
Also, a weight loss that may turn out to be significant would be easier to notice with more accurate measurements.
As for measuring length, I just measure their sheds and call it close enough. Easier than holding them up in a corner between walls to get 'em to straighten out.
-P
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1.0.0 Normal corn snake (Frito)
1.0.0 Creamsicle corn (Tang)
0.1.0 Ghost corn (Raynham)
1.1.2 Bay of LA rosy boas (Rivet, Cali, and Cali's unnamed babies)
0.1.0 Cape Gopher (Mole)
0.0.1 African House Snake (Casa)