Even Johnny Carson knew that absence makes the heart grow stronger ergo his frequent vacations had the residual effect of promoting Joan Rivers, Jay Leno (back when he was funny) and numerous others who hosted his show in his absence, it kept him fresh always , that and a sharp wit to be funny and interesting and entertaing every day can be a challenge and I think Johnny knew this which is why he lasted forever and even with this formula some of his shows were stale. The proliferation of talk shows has diluted the quality.
