I can't find it in writing, but I think Bushido has a skill focus of 50. Confidence has a min skill of 25, so with a focus of 50, you will never fail at 75 Bushido.
But you can also Lightning Strike all the way to 120 Bushido. LS has a min skill of 50. I think I succeeded every time when I hit 100 Bushido, but I still gained Bushido beyond 100 and hit 120 using LS.
Are you trying to squeeze a tight build with Bushido? I can't see any real reason to go with 75. IMO, Confidence alone is probably not a good use of 75 skill points.
-OBSIDIAN-