Should all domains lead to one Google Adsense account or should a person open several Adsense accounts if web-sites' contents do not cover the same (directory) category? What is legal, to have one Adsense account for all domains regardless to their nature or to have several Adsense account, each to group sites with similar content (in example, one AdSense account for e-commerce sites, one Adsense account for sports sites..)?
One Adsense account per person. The only way you can have more without violating their terms are if each site is a separate business entity (legally), and then you can have an account for each site.
Only One is Allowed if you will open more accounts... your all account will be banned and you will never be allowed to enter... adsense again...
It is legal to use your adsense code on all websites you own so there is no need to open another account anyways.