Stole this from here:
http://www.dunedinfootballacademy.com/training-hours
On average, European academies train as follows:
Team Training (Average volume):
U12 and below: 41-42 weeks/year, 3x per week consisting of 4-5 hours training.
U13-U15: 44 weeks/year, 5x per week consisting of more than 7 hours training.
U16+: 45 weeks/year, 5x per week consisting of about 9 hours training.
Individual Training (Average volume):
U12 and below: once per week, 30-60 minutes.
U13-U15: twice per week, 90 minutes.
U16+: at least twice per week, about 120 minutes.