What you actually need to do is satisfy your confessor about the nature of your mortal sins, their gravity, your habit, and the frequency. However you achieve that is always a negotiation, and most folks enjoy a steady confessor who will forge a relationship with you. Canon law specifies “kind and number” of sins, but confessors have a much wider range of latitude. Personally, no confessor has ever asked me how many times I’ve committed a sin, if I didn’t volunteer it.