Unfortunately, this is largely relative to the individual and specific to the areas of inflammation or removal. Some people swear they have no benefit from good probiotics. I know, since a resection near the ileum and minor patches in the large int are present, for me it is generally 8 billion 1-3 times a day on an empty stomach. That specifically keeps my BMs solid and healthy looking and if I skip a day, I will have visible, unhealthy looking BM issues and limits to my diet becoming apparent.
It is largely unknown if you can actually have too much and what that dosage is, especially since every formulation is different. For me, if I keep taking 3 dosages daily (alternating between 3 different formulas) for a few days, I will have noticeably harder/smaller BMs and almost feel constipated. That might be a sign of too much of a good thing?
I personally like to keep my biome diverse so as not to allow the bad bacteria to become immune, so to speak, to a single formula. So I like taking GOL's Primal Defense *Ultra*, NOW's 8 Billion Acidoph/Bifido, and Jarrow's EPS. Though I don't see anything wrong with dosages upwards of 30-50 billion for those who need it, however, I have never really tried anything personally above 50 billion.