I don't know if HR communicates things ahead of making changes, but doesn't seem so. It can feel like there are more People/HR changes after the fact verses getting a heads up. It causes issues and culture lows, but not the worst. Communication in general is "effective immediately" rather than "in a month heres what you can expect". So it can be a damper on the mood and incredibly difficult to plan around. Expectations are set in stone until they're changed and it's too late to reset expectations.