I cut a kirf with my chainsaw for the first split on all big logs.
Sometimes on a piggy back stave on stuff that really splits easily, I will start the split, put the blade of a mattock in the split crossways (stave back down, belly up) and use the handle as a pry bar to turn the blade like a giant fro. On that rare osage that splits with the grain cleanly I can pop off a belly split in a minute or so by advancing my mattock.