The tiniest amount of leakage is too much.
Agreed 100%. Sure it's nice to have zero leaks but if it's a small, slow leak that doesn't seem to get any worse, and the repair is expensive and/or will put the machine out of service longer than can be tolerated, then most folks will just let it be until time and money allows a proper repair.While in theory I try to do what Flyweight said, but in reality a working machine doesn’t get the liberty of being perfectly leak free in my opinion.
There’s a lot at play here. Cost and time to repair said leak, severity of the leak, how dangerous is the leak, will it cause more damage if left alone, and is the leak hurting your environment such as the barn floor or pastures etc.
So there’s no set amount in my opinion as a general rule of thumb. It all depends.
That being said, I like all my stuff 100% dry and leak free. Leaks drive me nuts. LOL