Partially agreed, but whether the game is designed to require more than 50 hours or not you personally would be able to tell whether you were enjoying it by that point. I have hundreds of Skyrim hours logged, but would have stopped playing after only a few hours if I didn't like it. Conversely I tried The Witcher (first one) recently and just didn't get alone with it at all - about two hours in total. Elite:Dangerous, a very direct comparison to No Mans Sky, I've not really got along with either despite being a massive original Elite fan and a passably high-tier Kickstarter backer of this one. I'm glad the new one exists, but it's not for me. Logged time - 9 hours.
You get the idea. The game may well require more than 50 hours, but if you're not enjoying it you'll know well before those 50 hours are played.