Interesting,I use the same metric roughly: if it's boring for me, it shouldn't be used by my daughter. However with console games it's kinda different. I played yoshi's world with her, but I'm a gamer, so long term the game turns too easy (this is also valid for most of Nintendo games, i've been playing those for ages). However for my daughter the game is hard. Some parts even too hard.

All of this to say, you should account for the "experience factor". If the game is too easy for you with 0 experience, that's a bad signal, however if it's too easy because you have experience, the experience factor must be excluded. A stupid example could be making paper planes. I get bored fast nowdays, but that's because I built and colored millions of them as kids. My daughter struggles to fold the paper properly though, so that activity can't count as "boring".

Same goes for movies. If I would rewatch the movie, she can watch it too. Beauty of this is that I can pleasantly sit close to her when she watches it and I don't want to pull my eyeballs off.