[Wauthan]

Usually go with Edis' strategy and assemble a squad of searcher-finders asap. Most of the time this just means sending one of each highest tier national mage out to search each conquered province. Once the spellresearch meets the needs I hopefully have enough resources to create a minimum casting group that tosses spells at one province at the time. Starting with the welldefended core provinces and work their way in a spiral towards the frontier. In the mid and late game I tend to revert to Achasic record though since spellcasters are too valuable to waste on site searching. It's expensive, yes, but saves a lot of valuable time and manpower.

That said I don't think I ever do a dedicated blood, holy or unholy search. Would such a search even be rewarding? Just about all the blood sites cause unrest and can spotted that way. I never found any good holy/unholy site and they seem to be very rare as well.