One of the benefits of both Drupal and Magento training is that there are a LOT of existing materials out there. The platforms are in heavy use by millions of sites, and there are books, conferences, websites, DVDs and webinars on every aspect of both systems.
Our client sites are generally fairly custom, so we provide the additional information around the edges to make sure clients have what they need to run their sites day to day. We generally start with a webex session where we do a detailed walk-through of the new system, and hand off detailed how-to guides specific to the site and screencap videos for ongoing use. Our goal is to set you up well so that you can run your site day to day without needing a lot of external support, but we are also available for client Q&A in email and via the Support Portal.