Fluid payable time approval grouping

How does the time grouping in the fluid payable time approvals determined. In some cases I see  it to be time period wise for each employee. In such a case  it will show 2 different approval lines, if the employee has payable time pending approval across 2 different TL time periods. In some cases we find that the grouping is across time periods as one single item with all historical pending payable time showing up as a single line item.

How is this grouping identified or setup.