Unpopular Opinion: Study Openings at all Ratings

"... for those that want to be as good as they can be, they'll have to work hard.
Play opponents who are better than you … Learn basic endgames. Create a simple opening repertoire (understanding the moves are far more important than memorizing them). Study tactics. And pick up tons of patterns. That’s the drumbeat of success. ..." - IM Jeremy Silman (December 27, 2018)
https://www.chess.com/article/view/little-things-that-help-your-game

"... for those that want to be as good as they can be, they'll have to work hard.
Play opponents who are better than you … Learn basic endgames. Create a simple opening repertoire (understanding the moves are far more important than memorizing them). Study tactics. And pick up tons of patterns. That’s the drumbeat of success. ..." - IM Jeremy Silman (December 27, 2018)
https://www.chess.com/article/view/little-things-that-help-your-game
I agree, but I think studying typical structures and tactics as they pertain to the openings you play is far more important than studying tactics in general, which will lead to far slower results.
I would suggest that you guide your study by looking carefully at what goes wrong in your losses (at slow time controls). Sure, maybe it would have been better (hypothetical example) to play 5...Ba5 instead of 5...Bc5 after 1 e4 e5 2 Nf3 Nc6 3 Bc4 Bc5 4 b4 Bxb4 5 c3, but did anything go wrong subsequently? I don't know about your games, but, for many of us, a typical game is long and full of missed opportunities for both sides.

I propose Opening Beginners don't mess around. My recommendation: e4 or d4 as white. As black Sicilian and Gruenfeld.
Around 2010, IM John Watson wrote, "... For players with very limited experience, ... the Sicilian Defence ... normally leaves you with little room to manoeuvre and is best left until your positional skills develop. ... I'm still not excited about my students playing the Sicilian Defence at [the stage where they have a moderate level of experience and some opening competence], because it almost always means playing with less space and development, and in some cases with exotic and not particularly instructive pawn-structures. ... if you're taking the Sicilian up at [say, 1700 Elo and above], you should put in a lot of serious study time, as well as commit to playing it for a few years. ..."
"... As Black, I think that [players with very limited experience] would do well … playing ... 1...d5 versus 1 d4. … [After 1 d4 d5, if] White plays the most important move, 2 c4, inexperienced players might want to begin classically with 2...e6 followed by ...Nf6 and ...Be7 …" - IM John Watson (2010)

While chess players are young, they got Time. Time to study Sicilian and Gruenfeld. College students and employees have limited time.
Each individual should try to evaluate whether or not opening study is crowding out too much consideration of other aspects of chess play.
"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactics, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov

[edited the quote, but this is basically what you're saying]
Strategy and tactics books often organize their lessons by theme, so it's not just random positions.
Anyway, it's true that if you study openings in relation to the middle and endgame you'll learn all sorts of stuff (like strategy and tactics). But this isn't really opening study per se, it's studying whole games. Like an annotated game collection, and yes, that's very beneficial.
"... I feel that the main reasons to buy an opening book are to give a good overview of the opening, and to explain general plans and ideas. ..." - GM John Nunn (2006)
"... If the book contains illustrative games, it is worth playing these over first ..." - GM John Nunn (2006)
Chess is 99% pattern recognition, as in, recognizing patterns you have already seen previously. Therefore you should practice all aspects of the game at all levels. Obviously you shouldn't be studying everything on the same proportion; you should focus on feeling, studying what you feel you are lacking the most.