Is the hardest part of building a SaaS getting people through the door, or keeping them past Friday?

We track daily signups like a scoreboard, and a spike in traffic always feels amazing on a Tuesday morning. But then you log in on Monday and see a cancellation email from someone who paid on Friday and barely touched the dashboard. It makes you realize that an acquisition metric is just a vanity mirror if the product doesn't hook into their habits during that very first session.

How early in the onboarding flow do you actually know if a user is going to stick around long-term?