How to study openings more efficiently

Recently I have been researching on how to study my openings more efficiently and better. I already know some of the basics but I want to know how a strong and/or serious player studies their opening. Any comment will be appreciated.

You have a choice to make Neo. Take the Red pill or the Blue pill. If you take the red pill you don't follow rabbits like stockfish.

I think serious players usually go with Chesstempo/Chessbase and other similar platforms for openings

I play Blitz games and look them up. That’s how everyone trains up to Magnus.

PS: using sources like books, cb, lichess db

so many options according to the rating level and your objectives

analyse your games and find why you were behind the average evaluation or why you did not punish the wrong move of your opponent during the opening (Stockfish, database, as you want)
Build your own opening book, move after move, game after game.

Look for a high rated player playing the same opening as a reference.
Prepare 20-30 (or more) games of the high rated player.
If you have time : look at the endings (which wing ? rooks ending ? pawns ending ? ... ) and work on them.
After that : look at the positionnal themes of the middlegame. Work on them.

and finally, it is time to look at the theory

Play against Stockfish level 1 or 2 to get a good variety of responses.

I guess you have to find your personal method to learn openings.
Some 30 years ago, my method was :
- analyse my last game with a computer or a book, and find the first bad move I made.
- discover the next move I should have done, and don't look at the variations after that.
This way, I was able to build a personal opening repertoire.
Another method that I use now: I don't care about openings, so i'm forced to think by myself very soon, and I think it's a better way to play chess (at least for me).