Does having old and young players in your squad benefit your team in genral
not really. thing with experienced players is that they simpley are more experienced, with better mental attributes helps the team with their morale etc abit.
u can have a squad of 23 players and all the players aged 25 or less. or you could keep it real by having a balanced team with a few experienced players, some in their prime years, and some young talents.
its upto you as a manager to be honest.