You can play any note from the scale (and outside) really. It depends entirely on how you want it to sound.
Look at the transcribed line I've attached for instance. There's a lot of root notes, also some chromaticism, 4ths, 6ths. Bar 17 for example the chord is a BbM7. The line starts on the root note Bb, the next note is a G which is the major 6th, the next is an F the 5th, back to the G then an A which is the 7th.