Ooops. Sorry. It's the right hand I get the nails done on. Yes, I play right-handed like most people do.

I do use the thumb and three fingers when picking...depending on the picking pattern. Some patterns only require the thumb and 2 fingers. Thumb is for alternating base, naturally. The 3 treble strings can be played using either 2 fingers...or 3. If you use 3, then the ring finger takes the 1st string. This is useful in certain picking patterns.

Thumbnail is great for long strums too. Carter picking can be done with thumb and 2 fingers. Fingers do the strums in that case, brushing forward and back, thumb does the base.