Does your manager/unit adminstrator help on the floor when your unit is busy/short staffed?

This a total culture issue. I'm betting you see your ACNO/VP or CNO very rarely.
When in the manager and/or director, the first duty is to the the patient and staff of the unit you oversee. If you worked as part of my leadership team it was an expectation that the leadership from Charge nurse to Director would be on the floor in staffing if the unit was in need.

I have worked in 7 hosp. never seen any of them helping floor nurse.

Nope :(

Yes

Yes!

Yes all the time