The 720 rule: "It takes 720 Amp minutes per square foot to create 1 mil of anodized layer"
You can see a bit more on it here:
http://www.caswellplating.com/bbs/vi...;highlight=720
As neilfj said, units are important. If you are CC anodizing at 4.5 amps/ft^2, the 720 rule says it wil ALWAYS take 160 minutes to achieve 0.001" of anodized layer. Your surface area is calculated in the current density; it's always accounted for. If you are going for a 0.0005" thick layer, 80 minutes is what you are aiming for.
jtagger19, you can use a much higher current density than 4.5 A/ft^2 and anodize for a shorter time period to achieve the same anodized layer thickness, but you will not achieve the same results. Pore size is very important if you care about dyeing the part, and there is only a narrow range of current densities that will give you suitable dyeing characteristics. With the LCD kit, stick with 4.5-6 ASF if you want good results with the dyes.