If your visiting from Mumbai, there is direct bus from Mumbai to Shirdi, it takes over night journey. The crowd is huge on weekends and Thursday. Remaining days are quite fine. Half a day would be good enough at Shirdi. From Shirdi you get Jeep facilities available to travel to Shani Singapore which takes almost 1 and half to 2 hrs journey one way to reach the temple. The same Jeep will drop you back to Shirdi so half a day you will be back to Shirdi. The Jeep price is very reasonable.