What is normal for an affiliate marketer's campaigns?

[AffiliateNate]

As a relative beginner to affiliate marketing (6 weeks) I am trying to get a sense of what is "normal" for an affiliate marketer in the following regards. (I am not looking for concrete numbers, just ballpark figures.)

1. What is a typical number of campaigns that a successful affiliate marketer might run simultaneously? (i.e. is it single digits? 10s? 100s? 1000s? ...)
2. If you had to guess, what % of those campaigns would include a landing page instead of direct linking?
3. If simultaneously running many different campaigns, each with a different offer, and you add a landing page for many of these campaigns, do you buy a new domain name for each of the different campaigns? (Or might you instead, for example, buy just a single domain name and make offer-specific landing pages within it?)
4. When you are trying to grow new campaigns, how many is typical to focus on at a time? (Is it just 1?)

Thanks