Emotional difficulties of spaced repetition

A few people (Piotr Wozniak? Andy Matuschak? Michael Nielsen?) have talked about things like "why isn't spaced repetition more popular/mainstream?" Without digging into the literature, here's my own brainstorm of what makes spaced repetition emotionally hard for me:

• Feeling like a perpetual student in a subject due to spaced repetition
• Competence vs learning distinction means spaced repetition feels like effort without progress
• Spaced repetition constantly reminds one of inadequacies
• Iteration cadence for spaced repetition experiments -- slow feedback loop means you're often not sure if you're doing the right thing until months later
• Maintaining habits is hard, and spaced repetition is a habit