I have a female budgie that has one chick that is 20 days old. I was wondering if the hen should be leaving the nest more then she does. She only leaves for no longer then 5 minutes and that is at most three times a day. 

Thank you for any help given 

She may just be caring for the chick. She probably grabs food and then gives it to the chick, whilst caring for it.

Thank you. I now have the problem that she just attacked the male for going in the box. She has been letting the male in all the time before this. Should I remove the male? 

This isn't the morst uncommon,  perhaps just keave the male in for a while longer, and if she continues to attack him move him.