I went yesterday specifically to buy stuff that was on offer, and I'll go back for whatever else later (and use up some points). You do have to check your offers and make a shopping list of them, not just hope you get points by sheer coincidence.
10-20% of your offers are things you don't buy but might, based on your history...if you don't like these offers delete them or they will clutter up your offers quickly. You might get up to 80+ offers divided over 3 weeks and then the cycle starts again so you don't need useless offers in there. Go and scan your card 1-2 times a week to get more offers. Delete, delete, delete the irrelevant ones. Better, more relevant ones will replace them.
That's my advice.