We want to make this very clear. We do not want people using substitution for every little thing. Otherwise fights become long repetitive and annoying. We also dont want people getting dependant on them with cooldown times. The numbers are how many times a certain rank can use substitution in a single fight.
Genin: 2
Chuunin: 3
Jonin/SJ: 4
Anbu: 5
S-rank: 6