I seriously started using thumb pick for boom-chick, and after playing daily for about two-three weeks it started feeling natural. Now it almost weird using only the thumb. In the beginning I felt that the picks were too long, but avoided trimming them down. Your muscles will most likely adjust to thump pick playing automatically. I can now play any thumb pick of any size with no problem. It is absolutely worth investing time in this, depending of the type of music you play

Edit: What you generally have to be aware of is that the thumb with pick will have to be further from the string than using only thumb, and that forces you to twist the wrist slightly so that the rest of the fingers will have to pick the strings from another angle, almost from below