Whatever work u do ... do it with a target and in a set time ...in ur exams...i would suggest if u go thru the paper in 4-5rounds and solve the questions as per their difficulty level...those which seem easy,solve in 1st sight...need some calculation,leave it for the second...if lengthy, opt the third round for it...if u r not confident of it...leave for the fourth and if u have no idea...no look back at them.u WILL SAY LOT OF TIME FOR UR EASY ONES