So why, in the Enid Blyton books, did they only spend a term or two in some "years" and over a year in other "years"? I used to puzzle over this.
I think in Malory Towers they languished for ages in the First form (starting at age 12), and then whizzed through various 3rd, lower and upper 4th and 5ths, in a couple of years for all those 5 "years".