I would say no, it doesn't. Quality does. However, what about a drop in quantity (ouput) and quality (classic songs/albums) at the same time?
1980-1991 (11 years): 7 albums released:
Boy: One of the best debut albums ever. "I Will Follow" is a classic. The other songs are strong.
October: A weaker effort but good nonetheless. Unfortunately no classics.
War: A defining record for U2. "Sunday Bloody Sunday" and "New Year's Day" are classics.
The Unforgettable Fire: Pivotal record. "Pride" is a classic. I would argue so is "Bad" and a few others on here but they are not as well known to the general public.
The Joshua Tree: Their first Iconic album.
"Where The Streets Have No Name", "I Still Haven't Found", "With Or Without You": all classics. Almost everyone owns a copy of this album.
Rattle And Hum: The movie was panned by critics but the album contains "Desire", "Angel Of Harlem", and "All I Want Is You", all classics.
Achtung Baby: their second Iconic album. "One", "Mysterious Ways", "Until The End Of The World", all classics. Absolutely the biggest band in the world at that point, and were guaranteed a high place in the panthenon of rock gods at that point.
Ok so in 11 years, they had 2 iconic albums and at least 13 classic songs everyone knows.
Now let's look at 1993-2013 (20 years): 5 albums released.
Zooropa: Fans love it, was praised by critics at the time, but really was riding on the heels of the ZooTV tour. No classic songs (in terms of a wide acknowledgement).
Pop: fans love it, but no classics. The "Discotecque" video alone almost sank their career, in terms of turning people away from the album. The band itself pretty much disavows this record.
All That You Can't Leave Behind": the album that saved u2's career after the Popmart disaster. "Beautiful Day" is a classic, whether it's one's personal taste or not. This album returned U2 to their previous stature.
How To Dismantle An Atomic Bomb: "Vertigo" is a classic, largely due to the worldwide promotion of the ipod commercial.
No Line On The Horizon: some fans love it, some don't, but no classics and the general public couldn't have cared less. "Get On Your Boots" was perhaps their weakest first single ever.
However, the 360 was the highest grossing/most attended tour in history.
So, in that 20 year period, 2 classic tunes, one album that saved their legacy, but certainly not an Iconic album.
So.....