[AreaOfEffect]

I believe "automatic site searching" refers to the fact that the game will auto-select a province with each casting of the a site searching spell. Sure, you are prompted to select the province and the selection process can be flawed, but it at least chooses a likely candidate for each casting.

I remember when I had to handpick each province beyond the first site searching for that round. If you weren't careful, casting dark knowledge twice could easily search the same province in a row. 3 death gems down the drain.

Note: You can automate the process by setting the mages to cast the site searching spells as monthly rituals (shift+M). These castings won't prompt you to choose a target, which is usually fine, except for the flaws in the selection process. This method won't be very helpful when you are constantly draining your gem supply or if you've searched all provinces from the previous round. It's best for catching up when you fall behind on site finding.