I've been to many league academy venues and never seen one on a school site, although a few are shared with university sports sections. For what it's worth Ryton ranks as probably the most basic ( and certainly the smallest) first team facility I've seen.
Investment at any new site will involve not only laying new pitches of academy standard, but separate changing rooms for each age group and opposing teams plus refs. On a busy match day this might mean seven or eight different changing facilities (including showers) are required, plus offices and classrooms, and a parents' room.