If you leave it on the counter at all times, I think the general rule of thumb is to feed it daily. If you are an active baker and are in constant need of refreshed and active culture, that's fine. However, it does result in a lot of waste, depending on how much of the culture you reserve to feed and how much you use every day to bake with.
I keep my cultures in the fridge because, at most, I only use them once a week. If I recall correctly, the Classics Sourdough book that I mentioned previously suggests that you feed cultures stored in the refrigerator every two weeks. This reduces the amount of flour I am using for feeding, and in turn, reduces the amount of culture discard from a 150-200 grams every day to 150-200 grams every two weeks.
What I do: The morning that I am going to make the dough, I remove the culture from the fridge and prepare a small amount of active culture in a small glass jar that I will use for the dough. I then put the culture back in the fridge and leave the active culture at room temperature on the counter for approximately 10 hours (since it's getting colder, I've started leaving the active culture jar in my proofing chamber). That afternoon, I prepare my dough using the active culture (it will usually have doubled or tripled in volume over the 10 hours).
Ultimately, this means that I have to plan out my dough in advance and don't have active culture on hand at all time, but in practice it hasn't been a problem since I follow a consistent schedule (prepare active culture Monday morning, make and knead the dough Monday afternoon and proof Monday afternoon and evening, then store the dough in the fridge for pizza on Friday, Saturday, and Sunday).
According to my notes from the previous post, I established my Ischia culture on 2022.02.14, and I considered it "established" on 2022.02.24. I would have put it in the fridge after this, and my recollection is that I first prepared dough with it on 2022.02.28.
