See, it's like water to me. If you always have enough, and even too much, you never really appreciated the taste of that very simple drink. But when you're thirsty? You will enjoy every drop of your drink (as long as it's drinkable ofc).
In my metaphor, the undrinkable water was Halo 5. Halo Infinite (and to some degree, Halo Wars 2 actually) feels like a fresh and gorgeous drink a water after being thirsty, and I'm fully enjoying the drink.
I probably wouldn't feel like this if I got too much Halo Content during those 6 years, especially if it was on the same line as Halo 5 (personal opinion ofc, I know it has its fans).
Regarding sells, you could indeed make a parallel with Assassin's Creed, dropping a game very year or 2, and the latest one is the best selling in the serie, but as a fan, I got an overdose of this saga, and I'm kind of glad I don't feel the same regarding Halo.
See FUNKNOWN iXi , I told you earlier you could leave for 2 weeks without having to worry. ¯\_(ツ)_/¯