You forgot the pressure you push down on the fretted string. ;) This will also cause a vibrato effect. Although it is less favored on a fretted string, the technique is used to cause a vibrato effect on an open played string. By pushing on the string rapidly between the bridge and tuner locks.

I only use the first one for getting a perfect pitch to a flatter pitch, by sliding back and forth from one fret to the top of the previous fret. Rather than other methods that vibrate from perfect pitch to a sharper pitch. A cool technique. :) On the other hand the effect is rather small.

I dominantly use the second one, the third sounds alittle hard to control. Being accurate and in tune with pitch bending can improve a players technic. Not obsessively just with some control and aural knowledge.