Bass virtuoso Billy Sheehan explained why proper ear training is more important that knowledge of scales in his book, telling Bass Guitar:
"I don't know much about scales - I just know what I hear.
"Thankfully, through listening to a lot of genres, I've probably learned all of the modes.
"So I do know the systems and how they sound, but I don't know which is which or the Greek names for them. When I hear something, I know where to go with it - in more of a visceral, ingrained way than anything too scholarly!
"I wish I knew more, and I’m always studying to self-educate, but mainly for me it's just ears.
"I go with what I hear, so when I hear Steve Vai play, I know where he's going to go. I can anticipate that stuff enough to hold a note at the back or jump in there and deliver whatever he wants.
"When I play with Steve, I want it to be Steve's thing! I'm a sideman; I'm there for the guy whose name is on the ticket. He is like a brother to me, so I want to nail it even more.
"Playing with Richie Kotzen [in The Winery Dogs], there's a lot of blues and jazz notes in there - I always think he plays lines that sax players like Eddie Harris or Sonny Rollins would have.
"On the first Winery Dogs record, he played a solo on one of the songs and I swear I could hear the valves of a saxophone clicking! It's part of the sax tone… I don't know how he does it!"