If you are doing one 135 a day use D76 1+3 and discard.
If you are running a cine print machine 24/7 and fast processing, it is economic to replenish. and you are going to purge the whole machine regular.
You will need to check the pH, filter, etc.,... and a damaged frame not end of world.
D96 ( the cine developer) is real cheap to initialize and replenish cheaper than D76...
If you use a stock bottle for D76 with 135 one bit of film shard transferring from one film to another can make retouching real difficult. 1+3 is safer.
Deep tank for large format and prints maybe...
You need to be an organic chemist to design a developer and its replinisher the two are paired.