That's like asking me if running up to a 6'5", 370 linebacker and smacking him across his face is safe or not. There are variables that affect the answer one would give. If you are his 3-year old daughter, I'm pretty sure that you would have no problem whatsoever getting away with that. However, you would probably end up in a body bag if you had just slapped his daughter and tried to slap him also. So is it safe? For me, 1000% because I know what I'm doing. For you? I would have to know not only your level of experience, but which polisher you are going to use at what speed, the type of pad you are going to use and how much pressure you are going to apply. So as you can see, VARIABLES make answering your question with a blanket yes or no impossible.
Now if you were MUCH more specific with your question and asked me if doing EXACTLY what I did in my videos using the EXACT
technique and materials that I used in my videos was safe for a novice, I would say without a doubt, yes, as long as we are talking about a car that isn't 50 years old and where the paint has worn down to nothing. I am very specific with the advice and practices I use in my videos. I leave nothing to chance or question. That's the way your questions should be. It's the Marine in me. The military will teach you to cover all bases and leave nothing to chance because some idiot will do it the one way that you didn't cover.
I give you the warning label on the hair dryer that says NOT to use it while showering.
I have a rule of thumb.
I never tell a guy to do to his paint what I wouldn't allow him to do to my own. I would never allow you at your experience level to wet sand the paint on my car. With that said, I would never advise you to try it on your own car if your car is one that you actually care about. If not, you now have a template within my videos to remove scratches from your paint
as long as your fingernail does not catch in the scratch. If it does, it is beyond repairing without painting. You can diminish the sight of a deep scratch somewhat by wet sanding it but complete removal requires professional intervention. Since you have no way of knowing what is deep and what is not, never screw with a scratch and sandpaper if your nail catches on it. Just compound and polish it and call it a wrap.