Answer:
It really depends on what type of advertising and the message with it's level of purchase urgency. An in-store advertisement may have a last minute sale displayed in an aisle that will create an impulse buy whereas a television advertisement may make more of an impression and build brand recognition and trust over a time period leading to more sustained sales growth over a longer period of time. Many television advertisements though use impulse buying to their advantage with messages such as "30 minute expiration on this one time deal, call and order now". Branding becomes secondary, yet even those advertisements (infomercials) leave an impression over continued exposure.
It boils down to what type of advertisement, where, and it's frequency.