So aside from having very questionable balance, this game seems to be throwing math out the window for the most part.
Case in point, Rinne Sasuke's passive skill (we're considering Sasuke with full BT), the one that gives Fear. The stated propability is 50%, so reasonably you should expect it to happen exactly half the time more or less.
That doesn't seem to be the case a lot of the time. For example the current one-ninja-meta Naruto 6P. Sasuke is supposed to be a soft counter to his attack spam.
But nope, happens rarely if ever. Naruto's attack (when fully broken) is hitting 4 ninjas, i.e. entire team unless you have clones, summons or whatever.
If Sasuke is on that team, then Naruto's chance to get Fear is 50%. If he attacks 2x, it's 75%, 3x 87,50%, and finally 4x 93,75%
So mathematically, Naruto attacking the team with Sasuke 4x times in one round should be incredibly rare. 3x very unlikely
But no. I see it all the time in Arena, 3v3, Decisive Bonds, etc. And it doesn't seem to depend on the power levels too much. Either Sasuke is secretly nerfed, or Naruto 6p got another buff, because that's what everyone needs.
Or, more likely, the math in this game makes no sense.