Yeah, but at 1800 I switched to 1.e4 e5 and was mixing in some benko gambit when I was black vs 1.d4
I didn't know all the lines, I just decided to start playing it at tournaments, and things worked out just fine.
Openings aren't so important if you're solid in the other areas.
The first time I saw the vienna game OTB I had no prep beyond 1.e4 e5 2.Nc3 Nf6 3.f4 d5
I played 3...d5 not knowing any games or moves or themes or any hints at all after that. I outplayed my opponent rated 300 points higher than me (1800 vs 2100) and eventually accepted a draw in a superior endgame (like a wimp).

@IMBacon Thank you! I am reading some articles on this opening as well as checking his games on chessgames.com
@Preggo_Basashi
1.e4 e5 has tons of traps. And, If White is to play Ruy Lopez then I have to study. When I play 1.e4 d5, I can expect the major threats from White and then it becomes a game of tactics. Ruy Lopez... I don't even remember how many lines there are
https://www.365chess.com/eco/C60-C99_Ruy_Lopez_(Spanish_opening)