There is I'm afraid a ton of hidden content in every chapter. (Did you click on Annie's mug before talking to her for example? Or get the bad end, or etc etc....)
This isn't done to be difficult or indeed to make it hard for players to get everything. After all, you can't get stuck in H5 no matter what you do
But it was to try and make each players game different. So that the playing experience you have will, ultimately, be close to being unique as I can make it. Obvs for Chapter 1, it's possible to have multiple saves and eventually track it all down, but this gets progressively harder as the game progresses.
Again, this isn't me trying to ruin the game. Rather it's to make your experience of H5, yours and yours alone - and also to make your choices count....