I meant remember, not understand. You can understand something, but I specifically mean remember.

I think you're putting too much importance on the ability to visualize it. I can have a high-resolution image of a candle, but it's not useful for understanding that there's a candle in the picture - for that, you need to have parsed the image and understood what it contains. The visualization is just the source material. Similarly, when you read a book, you're not remembering what entire pages look like with all the words on them.

The problem with these kinds of things is that so much happens unconsciously that we're not aware of. You think remembering the image is important because you're unaware of all the processing that allows you to understand the image.

Almost all artists will tell you the ability to visualize is critical to be a good artist...