It depends...

No, really, it does. It depends on your standard of fitness, on how old you are, on how big an aerobic base you have, on how intense and hard your intense and hard days are.

But however fit you are, and however big a base you have, I can't remember seeing any coach or training manual recommend intense interval sessions on successive days, at least not on a regular basis. As a weight lifter you'll know that you break muscle down while lifting, and build it at rest. Cycling is similar in that respect. You get fitter as you recover and compensate for the effort.