RSA exists this way..
12051--12052---12071--12072--12051--12052..
In short, this is done to ensure that rakes have sufficient time to be cleaned..
Todays 12052 which arrives at Dadar at 23:05, will be used by 12071 in afternoon tomorrow..
Tomorrows...
more... 12051 will use the rake brought by 12072 today morning to Dadar.