No it doesn't. It means that you have a sizable lead that in most (almost all cases) cases teams have no chance of a comeback. Unless you have a five or six TD lead midway through the 4th quarter, there is not such thing as garbage time until there is like a minute left if you you are looking for 100%.
It is rare, but there have been cases where teams have scored 3-4 TDs in a span of a few minutes of game time. So there is no such thing 100% chance of winning the game with 8 minutes left. If you have a 23 point lead midway through the 4th quarter, you probably have a 98% chance of winning. That is garbage time.
*Peyton Manning overthrows Vernon Davis*
Phil Simms: Perfect throw by Manning, Colts CB lightly touching Davis's arm is why he couldn't get the extra 7 feet he needed.
*Andrew luck hits Johnson in the hands, drops it."
Phil Simms: Andrew luck forcing it here, to Talib who is just all over the play.
Nantz: Umm.. looks like it hit him right in the hands.
Simms: It did, but if Luck had thrown it so his hands had to face the other way it would have been a completion.