You should be able to wash with Licefreee Everyday Shampoo as a regular shampoo daily.  Washing with it twice is to treat an infestation as that will kill any lice in the hair, but if you are using it as a preventative measure or as a follow-up to treatment, once a day may work fine. However, using it this way may not take care of any new lice that might find their way onto the head which is why we recommend using it according to the directions and wash, rinse, repeat.