Hi Susan! Yes, some people advocate doing abs every day while others say not to. I personally feel that it is better to give all hard working muscles some down time. I feel that any muscle that is worked out seven days a week will either suffer from overuse injuries and/or eventually become immune to a challenge.
Also, there is the boredom factor. If a person works a muscle every single day, they will most likely begin to dread this routine and start to just go through the motions to get it over with. If this is the case, there are little benefits to be gained with this approach, and therefore it would actually be more beneficial to work the abs less times per week with greater focus and intensity per workout.