PTC Sites - do the ads always lead you to another one?

Tweet

Well, I decided to start trying the PTC and I'm a bit confused, and I'm going to try some more anyway. But - do they always lead to more ptc sites? Is there any actual companies advertising on them with ads to view, or websites to view, or are they just other ptc sites? I know its all well and dandy as long as we get paid, but how is this advertising if its just another site? which leads to another site, to another site all ptc?