Anki[1] can work well with some things. For example, I used it after reading through a book on SSH and another book on Sudo to drill configuration options that it highlighted into my head. My retention has been fantastic, and I can easily configure both these days.
My process for doing that was to read through each book on Kindle, highlighting as I go. I then go to my Kindle notes[2] and convert them into an Anki deck for each book. Then it's a matter of going through the deck whenever you have idle time: waiting in lines, TV commercials, bio breaks, etc.
[1] https://apps.ankiweb.net/
[2] https://read.amazon.com/kp/notebook