When you say old house site....is the house gone? If you can pinpoint where the home sat, don't detect directly on the house site ....usually filled in with everything trashy......
What type of trash are you digging....is it newer trash or old trash? Iron ,rusty junk? Start around the perimeter of the lot , look over any embankments for bottle dumps, where they washed their clothes and hung them up. Find the main walk route to the house and detect along their as well as any shrubs,trees flowers that were planted....like roses,lilacs,apple trees....
Do along the ruts .
When was the last time someone lived there? That can help in determining the type of trash you might dig? If the area has no buildings now, look for indication of sheds, smokehouse,henhouse,privvy,rock fences,coral,barns..... well,pump or water source.Is there a stream ,creek or river close....find the closest route from house area to water.
If you have discrimination on your machine, discriminate iron out...then detect the area only looking for solid silver,brass etc hits.....see if that helps to begin with.
I would dig it all if it was me because well... I like rusty old relics.....but if you don't have the time to thoroughly keep hunting this place then do the discrimination elimination first.......