The distance from Jaipur to Mount Abu is around 7 hours, so that means a whole day has gone by, and even if you decide to travel at night you would at least spend a couple of hours sleeping during the day. Like Anurag mentioned five days would be a tight schedule and it would be a holiday where you would be on the move all the time with the only time to rest at night when you sleep. If you are OK with all this then five days is enough, there are things to see in Jaipur but Mount Abu is more of place where you can view the mountains and see great views.