Agreed, especially in the puzzles. I'm not sure what I missed but Kate just disappeared when I didn't visit her immediately - I'm guessing Davy had something to do with it but the walkthrough stops mentioning her too. Without checking the walkthrough, I might feel like I'd accidentally locked myself out of a lot of content, but that doesn't seem to be the case as, like I said, she disappears from that too.
Photographs seemed to duplicate themselves on the phone quite a lot. I could delete most of the copies but one copy of the current wallpaper looks permanent.
I found that unless I used the walkthrough, I was probably going to miss things. For example - the walkthrough says to leave the librarian after charming her. My instinct would have been to go all the way. When charming Kate's mother, leaving at different points changes which "version" of her you get, but there's no indication that that's even a feature or what each version entails. Even in the walkthrough, it isn't made obvious what the difference between "MILF Slave" and "MILF Slut" are. Is one loyal while the other cheats on us, or is one a brainwashed robot while the other acts more human? Once you've charmed her, the walkthrough explicitly says not to send her after the dragon gem, but that would be my natural choice having seen the option there. If sending her to look at that time locks us out of content, the option shouldn't be there and highlighted in the same blue that unlocks content most of the time.
The puzzles seem pretty arcane, with the maths puzzles in Kate's homework requiring a pretty specific combination of random operations that I was never going to figure out, and I still don't understand the "sequence" in the animals question on the phone. I only got the 5 and 9 question correct because I saw the answer in the drop-down, I wouldn't have even realised it was an option otherwise.
Considering that the phone call between the sister and Davy suggests that you have a limited time to deal with him, I think that the "spam everyone with charm and see what sticks" approach isn't great - you need a lot of clicking around looking for targets and stones which all takes time. Some of the cases in which the charm doesn't work make sense, like with the sister, but for others I don't get it - if you try it on the mother you just get told not to, and the spell just fizzles on the shopkeeper.
Most of the replies here say that there's a lot of content, and the reviews are good, so maybe there's something that I'm just not getting, but it feels like without the walkthrough I would just be wandering aimlessly until something happens.