.prop () против .attr ()

использовать plt.subplots:

In [36]: import matplotlib.pyplot as plt
    ...: fig, axes=plt.subplots(2, 2)
    ...: for ax in axes.ravel(): #ravel axes to a flattened array 
    ...:     ax.set_xlim(0, 10)
    ...:     ax.set_ylim(0, 20)
    ...:     ax.set_xlabel('Label_x')
    ...:     ax.set_ylabel('Label_y')
    ...: plt.show()
    ...: