Whats so bad about a variable time lag with monetary policy?

Question

"Also, the lagged effect of monetary policy is also variable, as different sectors of the economy will be affected to different degrees, depending on their interest rate elasticity"--->>so what?

Answer 1

Uncertainty for the investment community and financial institutes.  It kind of points out the effects of intangibles on economics.  If it was an exact science it would be much easier.