Coursera's cohort-based schedules, deadlines, and graded assignments create steady momentum, while Udemy's on-demand model often encourages drop-off. Tracking where learners pause, skip lectures, or return after reminders shows which formats sustain engagement. Completion certificates, peer interaction, and instructor feedback act like "retention signals," similar to click-through data in analytics. In contrast, Udemy's flexible browsing can lead to fragmented learning paths and unfinished courses. Studying these patterns helps designers refine pacing, improve motivation triggers, and structure content for consistent progress.