Just give it a try, don't worry about what other people make. Just put it on your site for a few days and see if it works for you. For most people it does
Yes each site will preform differently. There are people getting payed 6 figured monthly, I don't see how it wouldn't be worth it. It all depends on your site.
some of my pages make X, some XX, and some XXX of course my XXX site makes XXXX which is awesome because it helps pay for my personal collection of XXX.
It's worth to have Adsense. With a month or two of hardwork. Just sit back and wait for the money baby.