“We’ve Always Done It This Way”
Change is almost always received with at least a little resistance. When someone says “we’ve always done it this way” it’s a signal that you’ll need to do more work than just the change itself. You’ll need to “sell” your people on why this specific change.
When planning for change, then, you should plan for the change itself in addition to internal persuasion time. Yes, this takes more time, and yes, you need to do this.