telephoto lens tip

Have you ever found yourself in a situation where you are in a fixed position and your telephoto lens minimum close up focus distance is beyond the subject?  Here's one way to solve the problem.  I came across this tip in the May 2016 issue of Outdoor Photographer, in an article by George D. and Kathryn Vincent Lepp.  They suggest adding an extension tube between the telephoto lens and the camera body.
This will reduce the close focus distance.  The example they used was with a 500 mm telephoto lens with a close focus distance of 12.4 ft.  Adding a 25 mm extension tube reduced the close focus distance to 7.5 ft.  They also suggest that if you add a tele extender between the camera and the extension tube you maintain the close focus distance while increasing the magnification. Pretty neat.  This is something else this Camera Junkie will have to look into, since I don't have any extension tubes.