Piano learners waste practice time on ineffective method books without knowing if they're using the right materials

Self-taught and formally-trained piano students struggle to determine whether their chosen method books are actually worth the significant time investment required for mastery. They lack clear guidance on which books deliver results versus which are outdated or poorly structured, leading to wasted practice hours, frustration, and abandoned learning goals. Current solutions (reviews, teacher recommendations) are fragmented and don't provide concrete evidence of effectiveness.