The scenario is that we are in Revit and working on a mechanical environment, thus we see Mechanical discipline and HVAC sub-discipline, and assuming no view template is being used or loaded. As with my first post, if we are satisfied with all the settings we can always create a NEW template from your current view, hence I said it is the same thing using a view template. We do not know whats in the OOTB view templates and we still have to change it to suit your requirements. When you open an new project using the Mechanical template, I 'believe' it carries the properties of the mechanical view template.
This is what I do, whenever I have piping, I duplicate the selected HVAC floor plan, then highlight this plan assign a new Sub-Discipline to this in the Properties pallette, say Piping, and this will be listed under the Mechanical Discipline, not in the plumbing.
What I am referring to “To not confuse myself, I just highlight all the Floor plans, Sections, etc under the Architectural discipline, then type in the Sub-Discipline”. is that in a mechanical environment, there is no Architectural views present, but it can be created if we duplicate a plan from mechanical discipline, we can move it to the Architectural Discipline if we need to draw say ceiling or wall. In my work we normally do not have architectural in Revit, but we draw the mechanical in Revit, so to use a ceiling hosted family you need to draw a temporary ceiling, though we can always use a face based family.
What I am trying to convey is you can always do anything to your duplicated floor Plans/Sections and move it around to other Discipline or Sub-Discipline, you can add new Sub Discipline, say you want all the plans under the Architectural discipline, highlight (use the shift key) everything under the Architectural Discipline, and change the Sub-Discipline in the Properties by typing a NEW one OR select from the dropdown list.
As said before you can save the current view (plan, section or 3D) to a NEW view template and use it to your current view.