As posted above, a standard form was issued to every parish in 1811/12 and all ceased using their existing format, which is why those up to that date have been placed in archives.
Parishes only recorded Baptisms, Burials and Marriages, even after that date, there was no requirement to record Births or Deaths, although some did, hence in 1837 when Registration commenced only the marriage records changed, when Church records started recording on copies of the actual marriage certificate, the existing record books for baptism and burials continued. These books held a lot of entries and small parishes took many years before the books were completed and found there way into archives.