If the checkbox is on – temporary render results saved in OpenEXR Multilayer format including all layers and passes for future use. Only finished image compiles automatically, different passes need to compile manually.
Compositing nodes for final image combining connected to a separate output Compositing node and removed each time partition render starts. That allows to re-render image without manual editing compositing nodes.
Blender add-on allowing to interrupt the rendering process and resume it from the interrupted place. For those who are not able to have the powered-on computer for render for a long time.
For example, the whole image render takes 12 hours. And there is no way to have the computer powered on all the time, but it is possible to power it on for 5 hours with breaks. If you interrupt the standard rendering process to turn off the computer – next time render starts from the beginning, and all progress is lost. PartitionRender add-on allows dividing the image into several blocks – partitions, each of them is rendered separately. Choosing division by X and Y in 2 parts, the image is divided into 4 blocks. Each of them will be rendered about 3 hours that fit in the time to work. Each partition after rendering saves to file. The next time (after rebooting the computer) PartitionRender automatically continues with the partition on which the break occurred. After finishing all partitions renders, partitions automatically compile to the whole image in compositing.