If he is only doing 1 hour a week on his own in addition to team/odp training that is not enough. If he is an early-developer and/or superior athlete he might make a DA team and do OK for a while, but he will need much more than 4-5 hours/week to develop the kind of technical base to play at a higher level.
If you are concerned about burnout when considering an additional 1 hour/week on top of 3 team practices and ODP, his current level is probably right for you. 10+ hours/week is common for (boys) DA players.
The real questions are, what does HE want, and how bad does HE want it?