turnOffDefaultMaterial.py

# ---------------------------------------------------------------------------- #
# This scriptjob will turn off the default material option on each viewport

from maya import cmds, mel

def turnOffDefaultMaterial(*args, **kwargs):
    allIconTextCheckBoxes = cmds.lsUI( type=['iconTextCheckBox'],l=True )
    for iconCheckBox in allIconTextCheckBoxes:
        if 'UseDefaultMaterialBtn' in iconCheckBox:
            cmds.iconTextCheckBox(iconCheckBox, e=True, value=False)
            parent = cmds.iconTextCheckBox(iconCheckBox, q=True, parent=True)
            modelEditor = parent.rsplit('modelEditorIconBar')[0][:-1]
            modelPanel = modelEditor.rsplit('|')[-1]
            modelEditorPath = modelEditor + '|' + modelPanel # Couldn't find a way to get the long path from lsUI :(
            mel.eval('modelPanelBarShadingCallback("UseDefaultMaterialBtn", "{0}", "{1}")'.format(modelEditorPath, parent))
    print 'Default material turned off'

cmds.scriptJob(event=['ToolChanged', turnOffDefaultMaterial], runOnce=True)
cmds.scriptJob(event=['NewSceneOpened', turnOffDefaultMaterial])