the stretch is in the sight reading
Well, I like the brute force method in memorizing. Read through the work, then repeat until you can bring the sheet music in front of your eyes or transcribe it on a blank paper with correct articulations, dynamics and stuff. That's why my repertoire is so damn small
Also I take more breaks, and have more, shorter practice sessions throughout the day. This technique shows up in research on general teaching and learning as "distributed practice" and "spaced repetition" so I know it's not just me. Has to do with how the brain makes connections and transfers things from short-term to long-term memory.