they can b useful but hardly.
always look beyond 650 atleast if u r appearing from punjab & to an extant for nwfp.
if elsewhere 600 & nothing else.

it is hard to get high marks in compulsory
roughly if u get 650 means 300 in compulsory & 350 in optional.
but always remember that the topper has 2 go beyond 60 in almost every subject just ask fida if u r not sure
best of luckkkkkkkkkkkkkkkkkkkk