Breaking while stumping you may consider the type of woodies you are using. I use bright colored hard rock maples for stumping because they are toughest from side hits like rocks and logs.
I've made a number of jigs and experimented with various splices and footings. As was mentioned two wing and four wing joints work equally well, as does a single scarf joint, just not as attractive. Have shot all into concrete walls, the joint never has let go. The wood just fails elsewhere.
Thanks again Blake, I'm looking to get the Arrow Fix tool ... I break my share of arrows while out stumping.
Are you using the same shaft material for your repairs?