Do you do peer review? You can use that CONSTRUCTIVELY to get a point across.
I can tell you, as the charge nurse of a busy unit, there are times that it probably looks like I am sitting doing a whole lot of nothing, but in reality I am working on staffing, getting coverage for other shifts, making phone calls, doing a lot of paperwork that gets shoved at me (audits, reviews, doc reviews, ordering, fielding computer problems, fighting with the nursing office that yes, I do really need those 2 other nurses despite what the staffing ratio says). And when someone calls me to help them, I may not be able to do it right then and there because I am doing one of these things. I will take an assignment if I need to, but then people still want us to do a hundred things for them and I still have to do all my other work that comes with being a charge nurse.
Sometimes, you need to walk in someone else's shoes. When I find out people are saying I don't do a lot or help them a lot, I get permission to orient them to charge and then they change their tune the first few times they are on their own. Staff have to be in charge when we are off (we only have one per shift, so that leaves 3 or 4 days we aren't there). Most of them decide that I do a lot more than it seems.