Yes, that is true but the practice swings are at the ball contact level. Not stroking up in the air. Pool players can do their practice strokes at table level where there are no balls. Maybe soon we'll see a pro golfer practice his putting stroke up in the air at eye level.
An in depth defense of "air strokes":
At the upper levels of pool, I think you see several players with something like this in their Pre Shot Routine. Years back, Jimmy Reid actually had a training/teaching cassette out dedicated to the topic of pre-shot air strokes. His argument was that using this as a habit over and over allowed a player to have an anchor to help them capture/maintain their highest level of execution/zone. This is similar to NBA players who have Pre-Shot Routines for free throws.
Something as similar as the air strokes by Shane help him to mentally/sub-consciously connect with all the time she has hit that given shot in practice... it breeds calm, patience, and confidence.
These pros play on against different opponents, on different tables, in different rooms, in different cities, and often time different countries... A consistent pre shot routine is one of the few anchors that creates predictability and commonality of experience for these players. It is a way of making the uncomfortable more familiar, which breeds consistency and confidence.
If you get a chance, ask Shane what is going through his head when he is doing these "air strokes". it is that mental process, which is tied to the physical action that probably is the root of the success of this habit. If you are really into sports psychology, and wonder if there is power in body movement in relation to individual psychology, check out the Amy Cuddy (well known Psychologist) book "Presence". It makes the argument that physical movements/poses/stances etc.... have a powerful psychological effect on mental state. We all know how important mental state is to the game of billiards.
One other thought... have you noticed the practice routines that Shane has used this last year... where he goes live on Facebook and practices.... that is brilliant..... he knows that those practice sessions are viewed by hundreds of people at a time, he builds in an audience to play in front of... which helps to prepare for him for tournament stages when he is being viewed.... or... when he is playing on camera/tv etc........ a really great way to simulate those types of spaces in a practice environment.
Peace,
Chris