The risky work is not flipping DNS. It is agreeing what a “customer” is when three systems disagree, and proving the new system can reproduce last month’s numbers.
We write field-level maps, run dual-write or dual-read windows, and produce reconciliation reports before anyone is asked to trust the new UI. Rollback is a rehearsed path, not a slide.
Train people on the jobs they do daily, not a 40-page module tour. If a role still needs a spreadsheet on day 10, the migration is not done.
