Hello
zoki79, it all depends on what you are repairing with each repair kit and the condition of the item you are repairing. There is no "fixed" % of repair rate for each kit.
In general, coins repair kit works best (larger % repair) for repairing coin-bought rod, and Pearl repair kit works better (more % repair) on repairing Pearl-priced rod, and old repair kit is good for repairing very small-size coin-brought rod. If you use coins repair kit for pearl-priced rod, generally it gives much less % of repair than using Pearl-priced repair kit (but, if you have many coins and less pearls, this is a useful way to prolong the life of Pearl-bought rod by using coins-bought repair kit)
In any case, they are designed so that buying and using repair kits to repair a rod is cheaper than buying a new rod (of same kind).