We're working on a series of sites that are all based on the same DNN setup. This means that when I create a new site, I first clone the setup from an existing one, and then branch out from there.
With the latest site, I thought I would get smart. The previous site had a lot of very specific skins (one for regular pages, one for syndicated pages, one for the results page, one for the details page, etc.), which I didn't think I needed. So I asked my coworker to help me reset every page to the default skin.
He helped me find the correct SQL commands, and in one fell swoop, I had all my pages reverted to the default skin.
Further along in the project now, I'm discovering that I really shot myself in the foot by doing that. If my goal was to have all the pages use the same skin, I should have copied the same code into all the skin files, rather than actually applying the same skin to all the pages - because I'm now going back through and applying the exact same skin setup to the pages as the last site, due to a bit of CSS complexity I wasn't expecting.
The lesson to learn? Allow for future complexity when setting a site up. A little bit of planning at the start can save you a lot of time later on.