Let's say you have to perform a 4-way case analysis and are given a choice between cascaded 2-way branches or a single 4-way branch.
What's the difference in branch misprediction penalties, assuming the 4 cases are random?
Denote the branch penalty by x (which is 15-20 cycles on Sky Lake according to Agner Fog).
With the 4-way branch, the worst-case branch penalty is x. The expected branch penalty is 3/4 x: there's a 3/4 chance of x penalty.