Having been involved in club administration and coaching it in both domestic, junior and senior representative programmes I see there is often a misunderstanding regarding development opportunities, programme revenue and player numbers.
There are several comments in this forum string that suggest larger player numbers in junior representative teams are a revenue-generating activity.
From my experience, multiple years as a club treasurer, this is not true.
Over the last 15 years that I have been involved as a coach, the limiting factor has been the availability of good coaches. Year on year, there are always more players trying out than there are positions available and this is due to the availability of a quality coach. Most clubs simply cannot get the number of volunteers to coach.
Most junior representative programmes train three to four hours a week, plus play on a Friday evening. Therefore it is training that makes up 75 to 80% of the development opportunity and the Friday night game only being 20 to 25% of the weekly activity.
At the club, I'm involved in the squad's train as a large group for the first 20 to 30 minutes of the training session. This is to ensure consistency of development for the entire age group. The individual teams then train for the remaining time as individual teams.
As a coach, individual skills training is important, but, so too is teamplay and concepts of team offence and defence. therefore as the skill level in the programme improves the need to have ten players, 5 offence 5 defence, becomes more and more important. This is why junior programmes take 10 players per team it is not about revenue raising and it is not about fear of cutting players.
Addressing the original post. How to balance teams between top age players and bottom age development opportunities.
Assuming that the programme you coaching is sufficiently large enough that the top two teams will be predominantly top age and the bottom two teams would be predominantly bottom age.
If the skill gap is so large that you believe your 7th to 10 players will not get more than 10 minutes of court time per game then I would suggest you put the bottom age player down a team so they can continue to gain game experience. Personally, I would suggest you should never pick a player to who you are not prepared to give at least 15 minutes of court time to per game.
Now I do understand this can be extremely difficult for a coach in their first VC opportunity. My suggestion would be to remember you are dealing with children and you are having a bigger impact on them than you realise. Do what is best for the player long term.