When I go out and about I generally use a card clip and one deck. If I have a moment during the day to practice I am good to go and if an opportunity for an impromptu performance arises I have quite a range of effects I am prepared to perform with only one deck. When I carry more than one deck(two or three) it is usually because I am planning a performance. In this case I don't use card clips. Card clips won't save that much ware and tear on a deck if you are literally throwing a deck in a pocket just prior to a performance. Furthermore, I personally think they slow down my performance. Even if it is only for a moment I feel the extra time is still wasted in my performance.
If you have a purpose for your card clip such as wanting to present yourself as a "class act card mechanic," then you should have a card clip for each deck and the card clips should be of the same model. I personally subscribe to the theory that you should not carry more than one deck in the eyes of the spectator. It brings to much "heat" on the decks you use. Carrying two or more decks is mostly useful for swapping stacked decks, trick decks(IDs, Brainwaves, ect), and normal inspectable decks. In that case all the decks should "look" identical.
As for the pocket management...that all comes down to how you dress and how many pockets you have available to you. What works for some won't work for others.