disclosure: HG Employee
that said, shared hosting is alright but I wouldn't advise putting your high volume sites on shared. if even one of your sites starts to consume too many resources, you run the risk of the entire account being suspended (on the spot, you may or may not get notified either depending on your contact info) until you fix the problem.
I see plenty of 'affilliates' daily (i use the term loosely because many of them are simply guru groupies) who will throw up a WP site, 70 plugins, and wonder why we suspended them a few hours/days into having their site up. However the better affiliates know what they're doing and have their sites optimized and work fine on shared, or they move to a VPS or Dedicated server (which for the most part, if your server is acting poorly its your fault, not the hosting company).
In any case, I do alot of testing on my HG accounts, but my primary stuff is on a VPS with Linode.