c060 Madara Uchiha
 

Madara Uchiha has "may" in his effect.Does that mean you can activate it's effect multiple times a turn?As far as i know that is what ''may'' stands for.
For example if i have the client in play and Spiral of Pain can i use Madara's effect multiple times per turn to draw multiple times from Spiral of Pain?

No. You can only deploy 1 Ninja per turn.

That wasn't my question though. I'm asking if I can activate the client's effect multiple times, since it has "may" instead of "can".

You can only activate c060 once per turn.

That doesn't what "may" implies. You should errata it with "can", otherwise it makes no sense.

c060's effect is written as an activated effect that can only be used once per turn. The "may" is irrelevant since you cannot apply an activated effect multiple times off of a single activation.