Optimum lasers for hair removal (LHR)?

Dear Laser (LHR) & IPL expert device users,

Why you choose different laser wavelengths based on skin colors only? Should the depth of hair roots/follicles also take into account?

Says, using Alexandrite or Diode for Skin types I to III with shallow hair roots;
Nd:YAG for all skin types with deeper hair roots

What wavelengths & setting should I use for Skin type IV to VI with shallower hair roots? Nd:YAG can’t see shallower hairs, can it?

My propoal could be wrong so please feel free to commend on this.

Thank u,
Nora