Some of the ways an Advisor will try to satisfy your schedule include alternative sections of a course, or switching several sections around to fit in an open section of a course you need, or to fit in an alternative course for now and recommend delaying the course that is closed to another term. The Advisor may recommend substitutions of other courses you need for the one you wanted to override for this term. The Advisors know the best ways to rearrange the overall sequence of courses so that you maintain program integrity and do not violate necessary prerequisite requirements. There are some situations for which no other solution except an override can solve the problem, e.g. a senior graduating this term who needs a specific course in his major, and it's closed. An override will not be given for a closed elective course however, when there are alternative electives available, even for a graduating senior.
Many students have jobs which place constraints on their time.
The Advisors are happy to work with you as long as it takes to arrange a schedule that will fit your needs in terms of times and requirements. Remember, overrides are exceptions to the normal scheduling process and will be granted only when no other solution is possible.