I'm not a webdev, but I do a lot of infrastructure support. My company runs a few sites in DNN. We hired a web developer to make some changes and work on a couple new sites.
My experience with CMSs in general has led me to believe that you do most of your work at the top level of the CMS and largely leave the resulting files alone. The webdev I'm working with is adamant that they should be able to safely AND effectively edit the resulting files that get tossed into httpdocs and such. Given that said webdev is consistently breaking the site... I'm fairly sure not. Though, to be fair, some of the things broken had apparently been around for a minute, but I'm fairly certain the site is now running smoothly.
It just seems to me that for a dynamic CMS like DNN (or Joomla, or Wordpress, or Drupal...) that this person is approaching it, maybe not incorrectly, but certainly problematically.