"Habits vary," was his cryptic response when asked about his tight work schedule and not availing a single holiday since he took over as Prime Minister in 2004.

Singh was talking to reporters on the sidelines of a function at Rashtrapati Bhavan.

Unlike his predecessor Atal Bihari Vajpayee, who went on vacations during his tenure, for the economist-turned-Prime Minister it was work all the time.

"It is like any other working day," was the reply of his aides whenever asked about the 75-year-old Prime Minister's programme on a holiday observed nationally.

The work schedule is so crammed that the Prime Minister worked from his home on Saturdays and, if required, on Sundays without any break, they said.