I think it is ideal to have all day (or night) or 24 hr turnout. But I think many other plans can work. If a horse isnt getting significant turnout, it at least needs daily activity including some low-stress exercise (not always training). Horses that are working hard can adapt to limited turnout better than those that are lightly ridden 2 or 3 times a week.
I have always lived in the Northeast, so have always been able to find boarding stables offering some turnout. It does surprise me how many Ammies not in a program still opt for the fancy stable that only offers a half hour of turnnout rather than the plainer stable with all day turnout. We had an OTTB come from one with the warning that he “doesnt turn out”. BO put him in a paddock next to my horse and they immediately started a game of “got your face” and he happily stayed out all day from day one.
IME in my region, no turnout was most likely in barns specializing in Saddleseat (at least during show season because of the shoeing and wanting to have “brilliance”), and Stock horse Halter and WP (no sunburn or scratches!). Some of the bigger H/J barns do very limited turnout with some horses getting none.