In "blink" they explicitly tell you that weeping angel's only turn into statues when observed. They physically do not exist when unwatched. They do not have a choice, they were biologically programmed that way. I found this the most interesting part about their lore so i hate that not only do they show you that they do exist when unwatched, they also show them moving as statues. There's a lot of thing about this episode that i hate (especially the unnecessary lore additions) but this pissed me off the most.
Edit: I may have misread when the doctor says "They don't exist when they are observed" but I think my point still stands. They clearly had a different vision about the weeping angels when they wrote "Blink". What does "they don't exist" mean in this context? That their physical selves stop existing and they turn into statues?
I had a dream where I was the oldest and the worst version of the doctor. The doctor had killed anyone and everyone who could or have harmed me (billions of people). He killed friends and enemies. Finally I rest alone but I become obsessed with the bad wolf. I thought she would see what I'd become and finally end me. I would see the words "bad wolf" everywhere but next minute they would be gone basically going crazy. Finally the bad wolf would come and I would beg and cry for help and mercy but I've killed anyone who would or could help me and it was too late for mercy. The episode was called "The boy who cried wolf"