tapping your foot when playing by yourself for timing may not be that crucial. However, if you are playing with some one else. Timing is critical.. You don't want to be playing a C chord while the chord has changed to G. A freind of mine plays very well by himself, does lot s of solo gigs. But when he plays with others his timing is way off. Even if you have a drummer for timing some instances you have to count beats. I also play the Bass, so it's my job to keep the band grounded, So you got to tap your foot, bangyour head, wink your eye or what ever works to you keep the groovyness in groove...