Repairing a brick-wall

Wiki is saying: "Requires 20 Bricks to repair a segment or cornerpost; requires 1 Bar of Pig Iron to repair a gate".
Is that information obsolete or does it need some specific criteria for it? Because i hit my wall a little bit, and it looks like repairing 1% of it requires 6 ish bricks. So repairing a close to broken wall would cost close to 600 bricks and not 20.
But in this case i broke my own wall, do the 20 brick repair cost apply if the wall is destroyed by outside forces?
Is that information obsolete or does it need some specific criteria for it? Because i hit my wall a little bit, and it looks like repairing 1% of it requires 6 ish bricks. So repairing a close to broken wall would cost close to 600 bricks and not 20.
But in this case i broke my own wall, do the 20 brick repair cost apply if the wall is destroyed by outside forces?