To add to it, I always kept the manuals around, because remembering the key press sequences was akin to doing combos in arcade fighting games.
A few months without doing them, and it was hopeless trying to remember how to do them again.
The button press sequences are still combo-style; when I set one of the alarms on my ABL-100WE, it always ends in trial and error. I mean, basically it's logical, but when the buttons change what they do (e.g. when the display says "SET", the light button becomes "up"), it throws me off.
I always followed trial and error until I reached my target and I had the feeling that my results were much better than if I were randomly clicking buttons. That is, some memory always remained. Or the menu is well thought out and has some consistency.