i haven't ever heard anyone talk about this, but i've been playing the same bass for 8 years (a pbass copy). anyway, it has one of those thumb rests/shelves, and so i've always played with my thumb on the shelf. it never seemed like a problem to me or my teachers, but eventually i hit a rough spot - when i play other people's basses (like at the studio) and when i am looking to upgrade to a newer bass, i don't feel comfortable without the shelf. i can still play ok and all, but i'm just not as confident of comfortable. so my question is: where do most bassist put their thumbs (or is there a "right" place) when they play? when i play a bass without a shelf i usually rest either on the corner of the neck (byt the highest fret) or on the top edge of the pickup.