That percentage is the amount of your repair skill that is used to calculate starting condition. It has no impact on later repairs.
IE: You have a repair skill of 50 and one schematic, the starting condition of the weapon will be (50 * .75) = 38%
Same repair but with 3 schematics it will be (50 * 1.25) = 63%
Regardless of your skill level and number of schematics, you can't get one in better than perfect condition. So at 100 repair with 3 schematics it will start out in perfect 100% condition, same as it would be with 100 skill and only 2 schematics.