Scoring trend does not remain the same but changes. I have not opted Philosophy but if you are opting Political Science then I'll recommend you to opt Constitutional Law instead of Philosophy. Philosophy will cover 50% of paper-1 of Political Science but Constitutional Law will cover 60-70% of paper-2 of Political Science. Besides this, Constitutional Law will also help you in Pakistan Affairs, as one question in Pakistan Affairs is usually constitution related.
PS: If your personal interest is in Philosophy and have full grip on it then ignore my suggestion.