Somewhat depends on the type of line in your kit ( and the weight of your rod as well as water depth/speed to be fished.) With lead core ( line and kits) I make 2, 4 and 6' lengths. In most cases only 2-4 are needed and or tolerated by a mid eight rod. With the kits made from sinking line, longer lengths are desired and easier to cast. . 5 and 8 sounds like a good place to start if your kit is not lead core.