It seems that a few days of test-hole digging is normal. All of my girls practise for 3 or 4 days. They dig holes, cover them up, try somewhere else until they find the spot that's just right.
.... mind you, even after all that practise, not all of them get the actual laying technique figured out....
This girl always buries her head, leaving her backside exposed while laying the eggs. Don't be alarmed if you find your female buried head first in the dirt for a few hours, she's just getting close to actually laying the eggs.