In the past I have primarily built all my web applications using an N-tier architecture, implementing the BLL and DAL layers. Recently, I have started doing some RoR development
For certain pages, MVC can be a little overkill:
It's easy to get wrapped up creating a beautiful MVC architecture, when a small page, concisely written, can be OK on these situations.
MVC may also be impractical if you're in time trouble, and you need something out REALLY fast. Like your marketing team is out at a conference, they're having trouble, and needs something to show in their booth this second before they lose their biggest customer.