Each zone has a default green "treasure" (worth only gold) that you can dig up immediately. Digging that up also gives you a blue "treasure" lead (worth more gold). Finally, that gives you a purple "treasure" lead (worth even more gold). You can only dig up that purple treasure once per account per zone. But you can do that green-blue-green-blue treasure loop as many times as you want.

Non-treasure leads, like leads for furniture and motifs and gear, can usually be dug up multiple times but you need to find the lead again and many of those leads are rare. They are not like the green/blue treasure leads that are always available.