Sheet broke at user five; migrated in a Tuesday afternoon.
A 4-person consulting firm ran on a Google Sheets CRM for two years. They hired a fifth consultant and the concurrent-editing problems started in the first week. The migration ran on a Tuesday afternoon: CSV export, import to Strkr, mapping review, email backfill, team onboarding. By Wednesday morning the team was writing to Strkr instead of the sheet. The sheet archived 60 days later.