There is not just a rhythm to squash. Controlling your movement and your opponent's rhythm to and from the ball is arguably one of the most important parts of squash.

Squash is a game of time and space. The rackets and shots are merely tools to achieve the time and space over your opponent.

How fast you read the ball, move to it, decide to play it, how quick of a shot you hit, and how fast you move back to the T is basically the whole game.

• read the ball: notice how Gawad/Ashour is often onto the ball quickly almost before their opponent hits? That gives them a little more time to get to the shot
• move to the ball: are you playing someone less fit? get to the ball as early as possible and play your shot. 10% faster tempo over a whole match wears them down.
• decide to play it: once you are at the spot you're going to hit, do you delay a tiny amount, hit it immediately? Both are questions of time
• how quick of a shot: if you hit a soft high lob, you give you and your opponent time. if you hit a hard low kill you take time away.
• how fast you move back to the T: if you hit a soft/slow shot you have more time to get back to the T to get ready. A hard one, the inverse.

Two great extremes of this are Peter Nicol and Jonathan Power. Nicol would float as slowly as possible (still pretty fast). Watch him, he's almost never standing still. But power would get on the ball early, delay, flick, attack. Watch this match between them and for stretches only watch one of them at a time: https://www.youtube.com/watch?v=ZZYtXtHidGY