How Often Should You Practice Playing a Guitar?

Darlene has been learning how to play the guitar.  She practices every single day and has been wondering if she takes time off from practicing if she will forget what she has learned.  She needs to go on a vacation with her family but is concerned about not being able to practice while they are away.  She takes Online Guitar Lessons and has decided to send in a question to find out if they think if it would be alright to skip the lessons for awhile.  She was surprised to learn that they actually said they recommended taking time off and when she starts practicing again she would even be better.