Nowadays, a lot of softwares are available for automation of clipping images and clipping mask, so it depends upon your need for the situation. An automatic generated clipping path can save a lot of time and you will get a fine photo retouching in less cost but the accuracy of the image is enhanced through a hand-drawn or manually made clipping path as it is done by actual zooming by humans with the use of Photoshop Pen tool but it will take longer.