I think that’s exactly what people were referring to when they say “culture for specific bacteria”. Remember it’s not a bacteria species that phages target, rather it’s molecular signature on certain bacteria they target, and it’s a constant arms race in the nature, so there could be endlessly many possible kinds of molecular signatures found on what’s technically the exact same species of bacterium.

So they are not “breeding a phage culture for one bacteria”, rather they were breeding phage culture for the 1000 or so kind of molecular signatures, out of millions of trillions possible ones.

Yeah phages have extreme specificity just like most other viruses, and that is both a really big advantage and a really big challenge, on the one hand if you get it right you rest assured it will absolutely not harm anything other than that one single target bacteria you breed it against, no antibiotics can be nearly as safe in comparison, but then on the other hand like you said it requires you to take time and lots of work to breed a culture first before it can be used at all :/

Maybe in the future this process can be automated, and maybe we can even do genetic engineering to create engineered phages on demand in an artificial process that’s much faster… Oh well one could dream lol