Intervals are the foundation of music theory and ear training. If you want to have a highly developed ear, then having a deep understanding of intervals is key.
If you want to transcribe songs quickly, you need to be able to find what you are hearing on the guitar quickly. Guitarists can do this by knowing where every interval is on the guitar. And I dont mean figuring out after a minute. I mean immediately.
When you can identify intervals all over the fretboard, you can play up and down the fretboard, transcribe songs fast, and have way more fun playing the guitar. To know where all the intervals are, watch the video below.