when digging, is there a way to tell if the objects are buried close together, or far apart? also, does finding a shard in one area mean there are other shards nearby?

I'm not terribly good at digging and often only get half of whats avalible to dig out on one screen. does anyone have any tips on the best way to keep the fissure bar low when digging?

(I've found EVERYTHING but blue shards, down there, I swear.....)