Above is the smallest amount of policies way but I do it a different way. I have a policy for each server and backup type IE...
Server 1 has a full policy, differential policy, transaction log policy and a file system policy.
Server 2 has the same.
Server 3 has the same etc etc
This may sound crazy but we have such a diverse environment where extra backups are asked for or backups are asked to be paused one night that its easier for us to do it this way. Otherwise I would continuously be creating new policies for all the extra jobs and servers that needed to be removed from a policy because the were asked to be stopped would get forgotten to be put back in!
As long as you label every policy with exactly what it does its easy to understand and may even be easier for someone to take over from in the future!
Netbackup is such a great product that you can do most things different ways but I dont think any way is "The right way"
Sorry to sound confusing I just thought i would give you another option that you might find easier.
Thanks