Honest opinion: Its not a matter of size. Its a matter of completeness. Agile or waterfall processes fail if you omit the Qualification step, or if you don't ensure that the analysis produces actionable requirements, or clearly formulated specifications that lead to requirements, user/technical/or otherwise.

The whole point of agile is qualification through working software and getting feedback. There is no amount of analysis or requirements gathering that can compete with delivering an understanding of the requirements to serve as a model for how to move forward.

That Qualification step was the challenge I had when working on scrum projects in the past. I might finish implementing a feature in the current sprint #1, but QA won't get to start testing until sprint #2. When QA inevitably finds bugs, when do I fix the bugs? Should I have reserved an unknown amount time in sprint #2 for bug fixing? Or should I schedule time in sprint #3 to fix those bugs? If so, then the separate implementation/QA/bug fixing stages are each adding extra latency.