IF the exam is completed by 5pm or 6 pm, they have wait till next day 11 pm to board the train. It's again hotel expenses. Also, for cities like blr, if the train is 11 am, then you have to start from home at least by 8- 8 30 am.If its some corners like Electronic city, then add another 30 mins. Looking at this way, one sleeps that night to get early in the morning. Instead, if the train starts @ night, one can finish the chores and catch the train late night.