Sprint planning is supposed to take an hour. It takes three. And half the estimates are wrong because nobody fully understood the tickets.
The problem isn't the meeting format. It's the information gap. Engineers are estimating tickets they haven't investigated, in codebases they only partially understand, against deadlines they can't negotiate.
Why Estimates Are Wrong
1. Hidden Complexity
"Add a date filter to the dashboard." Sounds like a day. Then you discover: dates are stored as strings in one table and timestamps in another. The API doesn't support date range queries. The frontend date picker doesn't handle timezones. Suddenly it's a week.
2. Unknown Dependencies
"Update the user profile page." Turns out the profile page shares a data fetching hook with the admin panel. Changing the hook breaks admin. Now you're modifying two pages instead of one.