Spaced repetitions for openings make a lot of sense, but in my experience they work better for tactics. I improved a lot with a hacked up solution combining puzzles and spaced repetitions, and then created a website to make it easier for anybody to adopt that approach: https://chess.braimax.com
Lately I've been very busy with my day job, but I'm almost ready to get back to developing that website. Suggestions are welcome.