Over the past decade and half, Black Fridays and Terror Tuesdays have become a regular feature of newspaper headlines.

While other days have also been chosen to carry out terrorist strikes, there seems to be a marked preference for these days. With the Bangalore blasts on Friday, the list has further grown.

But is there a special reason why these two days are preferred over others by the merchants of death? According to political scientist Imtiaz Ahmed, terrorism is a rational act and terrorists have targets and purpose.

"If they think that committing an act of terrorism on a particular day would help them project a certain image and win the community's sympathy and support, they will do it," he says.

Ahmed, also an Islamic scholar, adds: "For them, Friday becomes a symbolic instrument to deliver a message that it is a Muslim act. However, it is also possible that a non-Muslim terrorist could use the same day to give out the same message and pin an act of terrorism on someone else."

Friday is a sacred day for Muslims. And traditionally on Tuesdays Hanuman bhakts go to temples. These are days of large congregation in mosques and temples. "To that extent, they become the preferred day for terrorists because it is relatively easier to kill the maximum number of people on these days," he says.

Security specialist, P R Chari, says that when a blast happens near or outside a temple on Tuesday, it means that the terrorists want to wreak maximum havoc on their intended targets.

"Terrorism is a murky game. Those who carried out the Bangalore blasts were also sending out a message. It was a demonstration of their capabilities and also a terse reminder of the state's helplessness," says Chari, research professor, Institute for Peace and Conflict Studies.