A lot of times actually. I stopped the Witness because I couldn't be bothered anymore. I don't like puzzles where they deliberately obfuscate information. And the reward wasn't there. I also put SMO on hold because I couldn't be bothered to find yet another 50 of the 200 million moons. It just became busywork that kept me from enjoying the game further. Finding one of ten trillion moons just isn't a reward, finding 20 of them isn't either. I remember the good old times when finding a Star in a 3D Mario game actually felt special because there was a limited number and not 73 quintillion.
Time sinks aren't inherently bad but the reward should be strong enough to make it worth it. So often times it's not busywork itself that discourages me, but the lack of reward.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.
