My cousin passed first try 57/65 with only using an app (it was takörkort app though). She e didnt read any theory book even once. She did however dedicate a lot of time to do the tests, go thorugh each chapter, try her best to understand it, etc. She spent arounf 1-2 hour per day for maybe 2 weeks so yeah, she didnt use it as much of a shortcut.
I did 90% of my theory studying using the same app, takörkort, and also watched a theory vid and a few pages of the book. I got the same score doing that, 57/65. Its not so much about where you choose to study (book, videos, apps, etc) its more about how much time you dedicate to it.
Gl.
Also try to understand what everything means, not just the correct answer to the questions if youre using an app.