Decide if buying a bundle is cheaper than buying items separately.
Bundles are priced against total list value, but only the parts you will use are worth anything to you. Discounting the unwanted extras by how much of them you will realistically use gives the value you actually receive; subtracting the bundle price from that is the true advantage. A bundle that beats the price of just the items you want is an unconditional win, while one that relies on the extras only pays off if you use them.
Bundle advantage
Value received = wanted items value + extras value x usefulness/100; bundle advantage = value received - bundle price
No. Retailers pick extras precisely because they inflate list value cheaply. Only the portion you will use belongs in the comparison.
Then buy the bundle regardless of the extras — the discount stands on its own and anything else is a bonus.
Yes. If you can reliably sell an extra, treat its usefulness as the share of list price you expect to recover.