It's been 8 years since I bought school shoes but I always spent a lot of money having them fitted and getting good quality ones. I have no idea whether the quality is still the same.
IME they lasted all year. I ensured that good leather shoes were cleaned and polished regularly as this helped preserve the leather. If you treat them well, they last longer....scuffs can get a coat of nugget over them
For me it was worth the $80-$100 (as it was back then) than paying $30 and having to replace them every couple of months.