its not the best idea. she could move over the eggs and tip them over, then they could die. You really cant go wrong with having them safe in the incubator. There you can monitor the humidity, the exact temp, and you can be sure theyve not been moved. The other main thing is, if theyre left with the mother itd be really hard to keep a eye on the health of the eggs because she'd always be wrapped around them, and unwrapping her could cause the eggs to tip over.With an incubator you can clearly see all the eggs so youll know if something is up.
Some people have had luck with letting the mother do it her self but most of the people i know who've done it had no luck. Personally i just think its better to be safe than sorry. Its your choice though