Technically we CAN use the work plane gird IF we are willing to set duct and pipe elevations at zero. Revit sees the work plane grid when the ducts are getting sketched at the work plane elevation, which is zero, if assigned to the Level. Hmmm, I suppose I could sketch a reference plane in section, name it, and then assign it as the work plane for the plan view I want to use and then turn on the grid, ow my eye!!
It would be helpful and nice if it were possible without any shenanigans. Here's a little video to explain what I'm writing about.