"However, I wonder why the same games are not just played the same
way all of the time by the winners over and over..."
Some players will go for the same trap over and over again, especialy if it has been succesful.
Marko Krale goes for (or has gone for...not looked recently) Blackburne's Shilling Trap 129 times.
Winning 90 of them as Black.
" On the other hand, why doesn't everyone use database information..."
Laziness and far too many games on the go is one answer.
The serious bods on here use a book or a DB to get into a playable
middle game but unless they are 100% dedicated it can olny be done
with a low game load.
I'd never use an online DB. Mostly because of what Paul says and who
puts these things together. In truth I don't even know where they are.
(and I don't want to know.)
I have in the past used an opening book looking for something in the small print
that maybe worth a try.
But usually I just rely on an old pet trappy line, my memory, or a line
or an idea from a previous OTB game.
If you were really keen one could use the RHP database.
That is good because it gives you info about the lad you are about to play.
It gives their games.
For instance if I was playing was you and I felt inclined I could enter
your name into the DB and I see that in your game v wildcats26 Game 1907705
You played 3.Nc3 v his Petrov and won.
(it worked for you in the past, so why ditch it.)
That's interesting, I played that OTB against Oliver Penrose to dodge his theory
and he played 3...Bb5 and got a good game. I'd play a Petrov and hopefully go into that line.
If no 3.Nc3 I'd be OK I know a handful of White lines I'd play the Black side and see what happens.
Also spotted in that game, not a bad player but not making the absolute best of his position.
Here instead of the slow and frankly useless move 14.h4 White should
play 14.Bxg7 which capitalises on White's previous good play.
(In answer to 14.h4 Black should have played Kf8 or Kh8).
So that miss coupled with (same game)
White played 20.Bxf7 here.
20.Qxf7+ Kd8 21.Nf6 is the wrap up.
Indicate that perhaps tactical play is not as sharp as it should be.
Also maybe the lad relaxes when he has a won game or has periods of
loose play, perhaps moving in a batch of games straight after work or
when he is being distracted by something else, going through the motions.
In short, a typical RHP player.
So I'd keep it flexible, don't force him to find only moves, just wait for the
blunder or dodgy ' I've run out of ideas (14.h4) type of move.'and pounce.
It's a game plan.