When you are learning a high-performance activity like a sport or musical instrument, the good coaches always get you to focus on only one or at most two things at any time.
The key value of a coach is their ability to assess your skills and the current goals to select what aspect you most need to focus on at that time.
Of course, there can be sequences, like "focus on accurately tossing to a higher point while you serve, then your footwork in the volley", but those really are just one thing at a time.
(edit, add) Yes, all the other aspects of play are going on in the background of your mind, but you are not working actively on changing them.
One of the most insightful observations one of my coaches made on my path to World-Cup level alpine ski racing was:
"We're training your instincts.".
What he meant by that was we were doing drills and focus to change the default — unthinking — mind-body response to an input. so, when X happened, instead of doing the untrained response then having to think about how to do it better (next time because it's already too late), the mind-body's "instinctive" or instant response is the trained motion. And of course doing that all the way across the skill-sets.
And pretty much the only way to train your instincts like that is to focus on it until the desired response is the one that happens without thinking. And then to focus on it again until it's not only the default, but you are now able to finely modulate in that response.
This is completely anecdotal.
But a years ago while playing beer pong i fuund could get get the ball in the opposing teams cup nearly every time.
By not looking at the cups until the last possible second.
If I took the time to focus and aim I almost always missed.
Yes, how, when, & where you focus your eyes is very key to performance. In your case, it seems like the last-second-focus both let your eye track the ball better to your paddle, then focusing on the target let your reflex aim take over, which was evidently pretty good. Not sure if I'd say the long-focus-on-target compromised the early tracking on the ball, or made your swing more 'artificial'.
A funny finding from a study I read which put top pro athletes through a range of perceptual-motor tests. One of the tests was how rapidly they could change focus from near-far-near-far, which of course all kinds of ball players excelled at. The researchers were initially horrified to find racecar drivers were really bad at it, thinking about having to track the world coming at them at nearly 200mph. It turns out of course, that racecar drivers don't use their eyes that way - they are almost always looking further in the distance at the next braking or turn-in point, bump in the track, or whatever, and even in traffic, the other cars aren't changing relative-distance very rapidly.
You were on to something!