In 1963 I was taught to grip the cue with 'All' fingers.
I can't remember a Top 3C players grip with the 'Pinky' sticking out.
The Grip
The proper full hand grip
The grip gives the player general control of the cue ball. Full finger grips are the most common choice among better players. The grip should rest in the palm of your hand; see
Photo10, instead of lying in the player's fingers.

Photo 10
The players that use more of their wrists give more rotation to the cue as it is swung back and forth. You may want to use a finger grip when applying maximum effect to the cue ball, (the cue ball maintains spin on 3 or more cushions.) For most shots in 3 cushion billiards, (especially short-angle shots), you want to use as little wrist action as possible, for better control of the cue ball, and a consistent hit on the first ball or cushion.
The simple move
The last element of a proper grip is the simplest. Most average players are looking for some magical move to make just before they strike the cue ball, well; I'm here to tell you, there isn't one. It's the simple opening of the hand on the cue when swinging the cue back,
Photo13, and when the cue swings forward closing the hand around the cue with all fingers,
Photo14. Also the middle knuckles on the cue hand, should be pointing to the floor. This along with the arm and the elbow in the correct position when addressing the cue ball will give the player a more consistent effect on the cue ball.