Check out www.carolkaye.com. Carol uses and teaches a thumb pivot for bass. It allows for covering more space on the fretboard with ease of movement, correct hand positioning, and prevents carpal tunnel damage. Take it from someone who spent years playing 12 to 16 hour days 7 days a week over many years, and hard playing at that. She knows of that which she speaks.
She also teaches to only use the first, second, and pinky fingers unlike one finger per fret for guitar. The reason is that the pinky and third finger share a common ligament and the third finger is the weaker of the two. It's OK to use the third finger if your switching strings on the same fret going from pinky to third finger or vice versa or for fast runs where it's light playing. Believe me, it makes a huge difference not only in your playing if you use the thumb pivot correctly. She has consulted with chiropractors and doctors over the years regarding avoiding crippling techniques. Hope that helps.