Cement sheet question

I'm not sure if I should have stated a new topic or not, but if I've done the wrong thing, I'm sorry.
Slightly related to the splashback thing.....but not in the shower recess....
On pulling off the old ceramic wall tiles, I've found that the original builder put plaster down to the tile line, then installed cement sheet, with no plaster under it. Is this normal, or should I replaster the whole wall and then install cement sheet over the top in the areas I want to tile. Not sure what is best practice here.

It is normal practice to tile over fibre-cement sheeting in wet areas and then use gyprock (preferrably Aquacheck) around the tiled area. The tile end up closer to the finished height of the plaster as the fibre-cement is only 6mm thick.

That's pretty much what I thought. When I did the kitchen, I plasterboarded the whole thing first then installed the cement sheet over the top of that, and I thought then that it was a bit of overkill.