To ensure easy communications the new product development team should be small. However if the team is small the risk increases - for example, if you have only one packaging designer in the team and he falls ill, all development processes are delayed. Think of a single lane road that is blocked by an accident.
Now if another team member can pick up the slack, the development processes can go on. Of course the specialist team member will be better at the job than the other team member. However for many routine tasks the alternative cross trained team member will be adequate though slower than the primary team member.
The same can be achieved by having reliable outside consultants who can pick up the slack. However the disadvantage when bringing an outside person on board is the time taken to make the person knowledgeable about the product.