There are different ways to play the same scale on a guitar, so patterns can vary. A scale pattern is 'correct' if it has the correct notes for whatever scale.

If you learn the notes of any given scale, and the position of notes on the guitar neck, you'll find you can also make up or extend patterns.

As for the claim that you only need three scales to be 'awesome', I'd file that with the videos offering to teach you to 'play like a pro in 30 minutes or less'