I beat Donkey Kong Country Tropical Freeze in 9 hours and only had difficulties on one stage... soooo. I think this one is just a patience thing. And if you don't have patience for it, it seems longer and harder than it actually is.
Also, depending on the game, it should be a medium difficulty with extras being the harder missions.
In RPG games, action and strategy games though, I believe there should be a difficulty option.
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