It all depends on what you are targeting and which methods you're employing.

Targeting 'iPod' and being number one would bring you an infinite amount of visitors and a flock of potential customers.  However, SEO-ing your site for the key phrase 'iPod' is an arduous task - and one I'd exclaim is near impossible.

SEO-ing for the phrase 'Red iPod Nano Sock Case' would be easier to optimise for, but would bring a smaller amount of visitors.  However, traffic is pointless if you're only attracting random wanderers.  I'd much rather attract 10 visitors that buy my Red iPod Nano Sock Case, than 10,000 that just want to read the specs of the new iPod, and have no desire to buy a Red Nano Sock Case.

I really should sell those, I always use them as my example - haha!

Source: Me @ Nottingham SEO