There are two major reasons to use a looseleaf service. The first is for the convenience of finding in one place various types of materials concerning an area of law. Primary and secondary materials, statutes and regulations, administrative and judicial decisions are all often found in a single looseleaf service (or database), such as the Standard Federal Tax Reporter.
The second major reason is currency. Most looseleaf services are updated frequently, sometimes as often as every week. Thus, they are a good source of up-to-date information in a particular area of law.