There are many roles in the IT world. In many large corporations they spread the IT workload across multiple, narrowly focused roles. In smaller companies, such as the one I work for, there is a small department of IT professionals that focus on all aspects of IT. The department is really small in my company; I am the only IT professional.
In my role at work, I am the hardware and software specialist, network engineer, server infrastructure specialist, help desk, and the list goes on. My first priority is to keep all of the employee computers up and running and thus one of my primary roles is desktop support. When I don't have to fix malware issues or crashing computers I work on the projects I develop to better our computer and server infrastructure. This might include extending our wireless network coverage, implementing networked video cameras, replacing aging servers, or virtualizing our physical servers.
These variables (among others) make my workload very cyclic. When things are busy, I often work 10-12 hour days (both at work and at home) and even nights and weekends. When my workload is light it gives me the opportunity to research preventative implementations and measures and develop future project plans (and I can often go home early, allowing me to work from home in the evenings).
The change of pace in my job can be frustrating at times but it's also welcomed. I appreciate being able to take my time planning initiatives but enjoy tackling time-consuming projects when the need arises. But don't worry, we just purchased $50,000 in software and $15,000 in server hardware that I get to install.