I'm a huge fan of spaced repetition and Anki. I strongly believe that most people's professional lives would be improved by using it. There is a huge amount of information that falls into the zone of it's needed often enough that not knowing it is a pain, but it's not needed often enough that you would "naturally" remember it. I've yet to find anything else that only takes 10 to 20 minutes a day that has a higher ROI…
Why is it useful? My job at least isn’t bottlenecked by me not memorizing enough things. Or maybe it is! But I’m not convinced
I think this could be less likely if you're very specialized, but if you're a consultant or freelancer and have to work with lots of different technologies, locking down the differences and unique aspects for each could save a lot of time.