Look at the active ingredients on most of the multipurpose cold/flu/headache medicines, and you’ll find that they’re all just various permutations of the same basic ingredients: acetaminophen (Tylenol), ibuprofen (Advil), naproxen sodium (Aleve), phenylephrine (Sudafed), diphenhydramine (Benadryl), dextromethorphan (Robitussin), and caffeine (caffeine).
So you don’t need Excedrin if you have Tylenol and coffee. You don’t need NyQuil if you have Tylenol and Robitussin. And you almost never need multisymptom versions of the regulars (e.g. Tylenol Cold and Cough, Robitussin Flu, Advil Exploding Nose, and whatever else they’ve come up with recently) if you just keep a few of the basics in your medicine cabinet. (Paying attention to the ingredients on everything also gives you a better appreciation of just how useful plain-old Tylenol is.)
I’m a big fan of taking as little medication as possible, so if I have symptoms I’d like to alleviate, I want to take only the relevant medications and nothing extra. Why fix a fever, headache, and stuffy nose with an everything-pill that also contains a cough suppressant?
Just get some big bottles of the basics so you’re prepared for nearly every common problem, and you won’t need to keep a million little boxes of random combinations that you don’t need.