I used to use a digital caliper from Harbor Freight and if you listened carefully, you could hear it munch on batteries. I swear it was a weekly thing to swap out the batteries, which is why I bought them by half dozen.
I later replaced it with a Mitsutoyo digital caliper and have had the same battery for over 3 years and have left it 'on' with display many times for a couple days. Granted the cost of a Mitsutoyo caliper vs a HF caliper can buy a lot of batteries.
When John Economaki was picking a caliper to use in the AMPv2 angle finder, he tested a bunch of quality brands. All the quality brands had the repeatable accuracy needed, but only the Mitsutoyo Absolute had the battery life. That's why I got it.