As I said in another comment, those are not necessary and really for people who feel compelled by them. I personally ignored them. You can’t ignore them in Riven
I was trying to find all the answers. Afaik, you had some way of knowing how many puzzles were remaining? Eh, both great games. Myst and Riven definitely have more of the "if you can't solve this you're stuck" vibe, I'd agree.