More than 60% of home battery installations inspected in Australia are ‘substandard’
(theconversation.com)
need to run every inch in conduit is goofy.
It's to limit the risk of mechanical damage. As an auto electrician, no way would I accept runs of unprotected battery cables (that is, only with their PVC insulation) in a fixed install. Too much shit can go wrong over the 10 year lifespan of these setups.
On a big battery system you need 150+ amps of fault current before the DC breakers even think about tripping. At 48 volts that's burn-your-garage-down territory if you get a nail or a shovel edge or a rat nibble across your cables that "only" pulls a hundred amps.