FindMyPast.ie has uploaded more than 43,000 addition records from County Mayo to its collection of Ireland National School Registers.
The entire collection now contains more than 186,000 records from 24 counties in the Republic of Ireland (counties Carlow and Tipperary are not represented). They span 1860-1922.
For further details of which schools are included in the collection and for the years of coverage, see this list. I suspect it was prepared some time ago but in the absence of any other details of the coverage of the latest upload, it seems to be the best we're going to get for now.