I separate sandbox games into two categories, light and heavy. A light sandbox is one where there is exploration, maybe some goals set that need to be achieved, and the ability to have more freedom of choice on how the story unfolds; I.E. Go into Sister1's bedroom before you go into Sister2's bedroom. Heavy is one where you have to get a job, grind up points for something, earn money, etc.
I don't mind light sandbox games, in fact, if they are well done I can like them better than VNs. I dislike heavy sandbox games for the most part. I have found a few that weren't too tedious, though this is rare.