I'd say that it really depends on the product ioksane. For example, if I was promoting the blockbuster total access, I probably wouldn't build a list, because if they're going to sign up for it they'll most likely do it from the landing page, and they can only sign up once so it won't do much good to blast people with the same offer all the time.
If I was promoting payday loans though, people who get one payday loan usually fall into the trap of borrowing money more than once. It'd be nice to be able to blast a list of proven borrowers with a payday offer a couple of times a month.
So, you're going to get the same answer as you would with a million other questions. It depends on the niche. Test stuff out and see what works for you.