Set a custom default label text

Almost all my plots have time on the x-axis so I was wondering if I could change the label to read 'Time [sec]' by default.

I have been looking into the get(groot,'factoryAxes') properties and it seems I can change the xlabel with set(groot,'defaultAxesXlabel'). However, when I change it to set(groot,'defaultAxesXlabel','Time [sec]') I get an error:

Error using gca
While setting the 'Parent' property of Axes:
Value must be a handle.

Error in newplot (line 68)
    ax = gca(fig);

Is this the right approach? Is it even possible to do this?