Very good thread. I do think SS is an advanced technique. According to my experience, if your level is 3.5 and less, you don't need SS. Let's you are in your 40s and you can play tennis 2-3 hours a week and your level is 3.5, I would say don't bother. because with that time investment, you are not going to get to 4.0 or 4.5, hence no need.
However SS technique can be a dilemma for some people:
if you are 4.0 and you play tennis 3+ time a week, your age is 30s and you are very into it and you want to improve to 4.5
if you are 3.0 but you are in your 20s and you like playing tennis a lot.
Although youtube has a lot videos about SS, I think most of them don't actually address the single core issue -- timing. They tell you a fixed answer, such as jumping on your opponent's making a contact. Some coach tells you to jump before the contact, or even right after contact. The truth is, they are all WRONG.
I am not a coach but I know logical thinking, so I know they are wrong: we all agree that SS's purpose is to start running quickly. So the principle is you want to start running right after you can judge the incoming ball's direction. SEE, there are many variables! that's why the timing isn't a simple easy answer.
let's list the variables:
1. you eyesight. someone can tell the ball's direction early someone can tell late. Generally under 4.5, you only need to tell the direction when the ball is on the net because that level the balls are generally slow.
2. incoming ball's trajectory. assuming you can tell the ball's direction when the ball is above the net, then how long does the ball take to travel from opponent's racquet to the net?
3. the distance between you and your opponent.
4. the angle of the ball: the more angle, the earlier you can tell the direction
HERE, I like to ask a realistic question: In what scenario, SS has best return of benefit against effort learning?
I think everyone should learn SS on return, SS right after serve, SS on opponent's approaching shot. Beyond that, anyone can give a list and timing analysis?