On the other hand, like for an experimental boat...
I have repaired 7 A-cat carbon masts (3 were mine): none has broken again where I repaired them. One 2-times-broken one split at the top when hammered in a pitchpole at high speed.
Of the others, 2 were crushed 1 meter from the bottom by being sat upon in slow capsizes. The rest were broken up high in blow-overs in windstorma (tie your boat down when not in use!), or violent pitchpoles in windstorms or thunderstorms.
Now, Lars Guck said to me, "I would never use a repaired mast" because of changed bend character.....but 99.5% of sailors would never know the difference.