Once a Week Computer Class? Application-Oriented Tech Curriculum?

We talk about computers in our classrooms, but are many students only using them once or twice a week in computer class? There are computers in other classrooms, but when are the kids using them? Before school? For a special project? When a mobile lab comes to the room? Does limited time to work with computers affect what students are learning about tech use? Are they simply, for example, studying how to use specific applications such as PowerPoint or are they learning media literacy and how computers can be used to enhance learning in different subjects?