Vertical dropdown menus have become a widely used navigational tool, mainly because they save space on screens with limited real estate. Over the years, users have learned to adapt to them. While dropdown menus have their advantages, they can also be problematic, especially if they are long. The longer the menu list, the more difficult it is to control. The further users must travel down the list, they more likely they are to lose their place.
It's often better to present long lists in standard hypertext format, where there's more room for descriptions that help people differentiate between the choices. Dropdown menus tend to be narrow and allow little space for descriptive category names. Rather than risk the chance of providing a long list of items whose meanings overlap or are unclear, let people click on the main heading and then take them to another page that clearly lists their choices with proper descriptions.