With the Idealism augment, you should stack your Hand of Justices on the same unit until you can split them on 3-item carries.

If you have 3 equal carries and 3 HoJ, it is strongest to have all 3 on the same unit since item scaling is multiplicative (i.e., they buff each other).

Keep in mind that if a unit goes on your final board, it can worth it to sacrifice temporary board strength to split them.

For example if you have two HoJ + IE with Zed 1 and Ezreal 1 in Stage 3, you may want to split your HoJ so you don’t get stuck with both together lategame.

Source: Aesah