If you are using one particular model, you can create an MC6 file, a Material Collection, that will apply the single texture/color over all the material zones of the figure.  If the intention is to create a material file for different figures, it would be better to create an MT5, apply it to one Material Room body zone, and perform the following steps:

1.  Right-click anywhere on that Material zone and 'select all' on the contextual menu.

2.  Once all the nodes are selected, right-click again and select 'Apply to all...' from the contextual menu.

3.  You will get a pop-up warning window, click OK to continue.

4.  Once you have generated the new texture, go to the Wacro panel and Shift-click on the 'Remove Detached Nodes' button to clean up all the zones.