OP has never said how much acreage he is talking about. Marking holes with flags or paint on 5 acres probably makes sense. Marking them that way on 100 acres wii result in many missed or lost. With a physical marker you have a limited time before animals, weather etc will destroy it. With GPS you can come back whenever and find it and you don't have to leave a bunch of marks all over your property. Trust me a gps will get you close enough to find anything that is big enough to need fixing. We bury hundreds of sensors the size of a one quart jar over thousands of acres. We use basic garmin gps units to find them. Have not lost one yet.