When do you absolutely need a pattern?

Dear users, dear authors,
what kinds of patterns do you prefer to buy? What’s important to you?

Right now, I’m on a clothing kick.

I buy a pattern when I see one that immediately blows me away.
Otherwise, I add the pattern to my wish list for later.

Best regards, Heike

I rarely need patterns when I’m sewing—the sewing pattern tells me exactly what to do. It’s a different story with knitting—I often find myself glancing at the pattern while I work, since I’m not quite that experienced a knitter after all.
One of my daughters always says to me, “Mom, patterns are just there so you have something to throw in the trash,” :-) ;-) but I don’t really see it that way.

Thanks for the responses so far.
Would anyone else like to add anything?