Sick Leave is a benefit to be used whenever needed. I make use of that benefit everytime I need it, "even mental health days" I still have close to 1,000 hrs in my balance, and I sure will not leave...
As you said... there is an unwritten rule. Why not write the policy? If the ICU is low census then those are the nurses to be floated. There is no reason to float Telemetry nurses since they are not...
Last year the Chief Nurse came around with a cart : cookies and Kool Aid. I asked her to work on giving us a coupon for 12 hrs Excused abcense to be used anytime during the year. (This is what we used...