In slideware (PPT) documents, I will use a format like this for titles of things that can't be broken into separate topics and stretch over more than one slide:
- Problems with moderators at ASE (1 of 3)
- Problems with moderators at ASE (2 of 3)
- Problems with moderators at ASE (3 of 3)
I do this routinely in the work world and see others do the same. So I think it works and is normal.
In general, I try to have different topics, titles. So if you can, great. But there are times where it would be too awkward to do this and it is just better to use the (1 of x) format. For example, if you have a numbered list stretching over pages and not easily separated into sublists. I prefer (1 of x) versus just (1) because audience can see where going.
You should also always number your slides on a PPT. But that is different from title issue. Is for whole document and is small and usually at bottom. Will not display in projection mode but is useful when printing the document or working with it. (Of course this does not apply to transparencies or slides in a carousel. Here the whole point is the flexibility to mix/match.)