This schedule is set up for teams that rotate 12-hour shifts that are on for one week, and then off for a few.
The following example shows three teams that rotate shifts:
The way to build a schedule like this is a little counter-intuitive. It helps to think of each person doing two different shifts, one week where they work Monday-Wednesday-Friday-Sunday (MWFS) and another one where they work Tuesday-Thursday-Saturday (TTS). So we have now two six-week rotations as everyone rotates through the MWFS schedule, and one staggered by three weeks, where they work through the TTS.
This generalizes to having N shifts a week, with a cycle of W weeks to creating N schedule layers with N*W team members in each (here N=2, W=3). Or, if you want some team members to always work four days a week and others always work three days, you can simplify your teams so that team one has only the three people working four days, and team two has only the people working three days.