Users don't read your app like a book — they scan it like a map. If the map is organized poorly, they get lost. And lost users leave.
Signs your IA is broken:
→ Users ask "where do I find X?"
→ Users use search for things in the main nav
→ Support tickets about features that already exist
→ Users create workarounds instead of using built-in features
→ Five clicks to do something that should take two