If you look at it from a research point of view, if you are only doing your own tree, and not a professional genealogist, you should be looking for maybe 2 grandparents, 4 great grandpaprents, or at the very most 8 great grandparents.
You should at least know their names and maybe their ages, and where they lived. if you add to that other siblings that should be at the same address, or parents, children that should be there, if the quality of research you have done on the 1901 or in civil registration,monumental inscriptions or Calendar of Grants has been accurate and confirmed, you should only need a few hours on there anyway using the free search, eliminating the unlikley hits, then cross referencing the districts to the hearest civil registration entry.
I have used it for a few hours on search only and been able to confirm the families i need were there and narrowed it down to just a handful of actual transcriptions needing sight of