Richard,
High dose probiotics are warranted in low oxalate diet programs. I will typically either use VSL#3 or ProBio Premium. Both are available from New Beginnings Nutritionals – http://www.nbnus.com. The dose is approximately 225 billion organisms.
Another situation for high dose probiotics would be after a course of antibiotics. For example, if someone took a Z-pak for a sinus infection than a high dose probiotic is helpful.
I don’t know how much benefit there is to dosing a probiotic multiple times throughout the day. I have seen people advocate for it, but I have not seen any major differences with people who have tried it.
The main thing I have seen is where taking a high dose probiotic causes loose stools, then sometimes splitting the dose in two can help.
Dr. Woeller