As far as I have noticed, Revit's scheme for numbering sheets is based of international or American style. Meanwhile, in Brazil we use a numbering style in the form of "sheet number / total number of sheets". While the current numbering of sheets allows to number individual sheets in this format, adding or removing sheets might be an exhausting task, specially for a very large set of sheets.
I'd like to suggest creating a couple of parameters available to sheet families, one being the total number of sheets and the other the indexed position of the sheet in the sheet set. However, it would also great benefit some uses I've needed if these parameters could retrieve these values from sheet groups on the navigator. For example, a set of 20 sheets with no grouping would provide the value 20 for the total sheet count and from 1 to 20 to index sheet. But if the navigator is configured to group sheets by the first letter (the demo project has this option predefined). So if 14 of these sheets have the A prefix and the remaining 6 have the prefix G, then the total sheet count would be these and the sheets would have the index between 1 to 14 for A sheets and between 1 and 6 for G sheets. Notice these new parameters would not consider the current sheet number in any way. Thus, even if the first sheet is numbered A101, its index number would be 1 and if the second sheet were numbered A206 its index number would still be 2.
With that we, at least in Brazil, would not have to resort to tricks and acrobatics in order to correctly number sheets for our projects.