The HubEngine manages the data transfer automatically.
If the selected endpoint of the connected API offers a method for mass processing (create, update), the function is automatically used by HubEngine. You can see whether mass transfer is activated or not on plan level in the plan overview of a group. If it is activated there is a gray box with the tag mass transfer at the top right of the plan (next to the box enable notifications).
With mass transfer, the data is processed in batches. For example, if 100,000 new entries are processed and a batch size of 1,000 is given, the data is processed in 100 steps.
The Mass Transfer function requires far fewer API calls, which reduces costs, and at the same time significantly increases processing speed. So the option is a thoroughly good thing. If you still want to deactivate the function, this is possible on request. Please contact the support team.