I went on many Tues, Wed, and Thurs back when SFMM was open 365. And there was nobody, I mean nobody there. From the guest point of view it was amazing, but I cannot believe it made them any money. I think being open 4 days a week is just fine for SFMM.
Let's not forget that Disneyland wasn't open daily for many, many years. I think the idea of parks needing to be open 365 is a uniquely SoCal concept. Anywhere else in the country, as well the world, that isn't really the case. The vast majority of parks have long off-seasons and weekend only operations. Parks that are open daily--in the entire world--could probably be counted on one hand (outside of Disney/Universal parks).