Each parish can be quite different. Some explanations are herehttps://www.familysearch.org/learn/wiki/en/Ireland_Tithe_App...
Couple of things to note.
1) PDFs are numbered sequentially, so if you want to browse them, just add one to the last number before the .pdf
2) There are a lot of pages that are digitized, but not indexed, so browsing as explained in #1 above is good.
3) The transcription is horrible, in many cases, so browsing is really useful.
4) I assume people know how to download the PDFs, as it is useful to save the records.
Hope this helps.