All I know is that if you create a new site this appears at the bottom:

Start watching: site blank-template.wikidot.com | category _default | this page [?]

i.e. not watching anything yet.

Though there might be a setting in the user profile that you have enabled (and I have it disabled) that makes you automatically watch any sites you create?

Yup. In account settings, Auto-watch sites I create or join, pages I create, edit or comment.

Is that set by default on new accounts?

As far as I know, yes, this is set on by default. I think this option is confusing, see my proposal for simplifying and extending the configuration page.

Just make the MA auto-watch a site, and everyone else has to explicitly click on the link at the bottom of the page. That means making the default user settings to not auto-watch sites that they become members of (but do watch pages that they create or edit)

@ leiger: That would be the ideal solution. See, a site is like an MA's kid. Although one's best friends may be willing to look after the little brats every now and then, they don't want to know every single detail about their lives — every diaper change, every booger clean-up, etc.

Now, seriously, I want to be able to assign specific responsibilities to different admins, having them looking after a specific category, for instance. That's what they may be willing to watch, if they want so.

@ pieter: For what types of sites do you envision watching as being necessarily automatic?