Not nearly as much as putting off the booking only to have the price shoot up overnight! At least if it goes down you have got the booking at a price you are prepared to pay. The other way round you may not be able to pay the price.
But to answer your original question, yes it does!
Not nearly as annoying as booking a flight on BA website yesterday lunchtime only to check my emails at 5pm and find they have sent me one offering special deals off flights - OK it was only �20 but �20 is �20 these days!!!!