A number of players have remarked on my game about how relaxed and effortless it looks.
I would not call it effortless, but in a lot of ways, I am not feeling hurried.
There are a lot of benefits to not being hurried, or to rephrase, having a lot of time. I try to be at rest for the next shot and I try to be at the best court location for the next shot.
I suspect that this looks effortless is that I am moving as soon after I hit a shot as possible, or if my partner is hitting the ball, I will be moving before he hits it. So if you are watching the ball, you don't see me move early, though it's always happening.
If my partner is hitting the third shot and it's going to be a drop or something less than a drive, then I want to be very close to the kitchen line and stopped when partner's shot is returned. I will, of course, alter my location based on where partner hits the ball. The rule of thumb is to move toward the ball, not just moving forward. I'm either expecting to guard a down the line shot, or a middle shot. Note that cross court shots go through the middle of the court and someone should always be looking for it.
(Pro tip... We all have patterns of play and in the early points watch what your opponents will do with a drive, for example. A common play is to try to dink as the opponents are deep. If you are expecting this shot, you will be able run up and return it. Also the players who live to hit the ball as hard as possible, are usually obvious about it, punish them by being ready to duck their out balls.)
I gain time to move and stop by moving as early as possible. I don't hit a shot and admire it, or expect it to end the point, I move to defend the next return. I don't mind stopping in the transition area, for example, if I expect the shot to head there and this is fairly common.
And part of defending a shot is having my paddle in a location that covers the most likely return; if my shot is high, I will expect a low shot to my feet. If I drop it well, then my paddle will be above the net and ready to block a speed up or to drive a pop up down to the opponent's feet.
And that is all it is.
Note that the faster the ball speed, the less time you have to move and thus even less time for admiration. Also better opponents will hit the ball harder and rob you of time too. You gain time by hitting slower shots that are low and can't be attacked. Soft sliced returns are quite effective. Dinks will also gain you time if you or your partner are out of position or are in a defensive position.