Memorization as Perception.
It’s okay to forget what you memorize.
To memorize a poem and to then forget (some or all of) it is like reading a poem and then forgetting it, only better.
Memory is part of perception. Memorization is a conscious effort to put information into long term memory. It’s still a good thing, even if that information doesn’t stay in long term memory forever.
During the period of time that the information (the poem or the diagram) is in long term memory, you get the benefit of it. You can understand the poem and the diagram better. You can recite the poem from memory, and draw the diagram from memory. The longer the period is, the better, other things being equal, but it doesn’t have to be forever.
When you read a poem that you know by heart, you understand it better. When you look at a diagram that you can draw freehand, you understand it better, and see it more clearly.
So neither BYKI nor ANKI software, nor any systematic reviewing schedule of any kind is really needed.
Memorized knowledge is perfect knowledge. It’s still worth having some perfect knowledge, even if it is not forever.
In other words, it is better to have learned and lost than to have never learned at all.