I agree with many of the posters that packet tricks are great... as long as you justify their existence. Audiences are smart enough to know something is up if you pull out four "normal" cards from a special wallet when you've been using the same deck of 52 all performance.

In that regard, they are best performed alone as a single shot, rather than incorporated into your regular set. Agreed.

However, there are plenty of packet tricks which totally justify bring cards out of a wallet. Blank cards or cards which are duplicates for example. The packet tricks I perform in my set all have a logical reason for coming from somewhere other than the deck.

That being said, I will usually only perform one packet trick per set.

Agreed. That is the best policy.