A turntable is but one option, sure. But they also require a lot of land in one single location (you need to consider the length of the cars that will be using it), and a lot of maintenance to keep the thing turning.
A wye is another, and was much more common back in the "good old days". They have their own set of problems.
A loop is the most-efficient way from a headway standpoint, as it allows for the minimum amount of time between cars. No turning or reversing movements are required.
Generally double-ended equipment will have door controls for both sides at each operating station. It allows for more flexibility, and the ability to have "off-side" platforms.
Dan