Like this week there's 2 codes for 6 shift keys total.
Do you use them all at once, or do you spread them out sparingly, or do you spread them out among all your characters? --- http://www.forzamotorsport.net/en-US/gallery.aspx?gamertag=TheBlueStig My Forza 4 gallery, all paintjobs available for purchase on my storefront.
I use them in between playthroughs and in between farming opportunities when I start to feel my equipment lacking, if not I save them. I don't use them with max level characters. I may also use them when I'm bored because I have 30 or so saved up which is common around these parts.
I stopped using them when I stopped playing the first time, months back. I still redeem the codes though. Dunno why. --- http://i.imgur.com/wiAJ9.jpg http://last.fm/user/AnathemaOfZos Gamertag: aGeorgeDivided
Use them when you need them. Don't worry about the optimal level to use one. If you're at a point in a playthrough where you're saying "damn, I need some better gear", no matter what level you are, that's when you use one.
There will be more shift codes, so don't fret over using what you have. --- Tool Spiral Out...