I deleted pages from my watchlist (mainly from the (Main) namespace) and changed the interval in special:Preferences to one day.
With this configuration I get result and the indication:
"1,348 pages on your watchlist, not separately counting talk pages. ..."
It is still *not* possible to display for example the changes for the (Main) namespace and for time interval 2 days (I manually changed the browsers url to days=2). I still get the heavy traffic error page with "503 Service Temporarily Unavailable"