As someone else said - The Beatles were only around for 8 years.
Most bands these days can barely manage 2 albums in that time.
Bands back then put out an album every single year. Sometimes two albums a year.
I read on Wiki that AC/DC put out Back In Black literally 1 year after their previous album - and they had to get a new singer in that time.
Back when I was seriously into music as a teen - all my fave bands put out an album every year or 2 years.
Now it's 3 or more as standard. If you're lucky.
Therapy? have put out 15 original studio albums in 30 years. Which is pretty awesome. And only 1 or 2 duds in there.
Rush and Kiss, for example, were almost at an album every six months.
Kiss February 1974
Hotter Than Hell October 1974
Dressed to Kill March 1975
Alive! September 10, 1975 (my birthday!)
Destroyer March 1976
Rock And Roll Over November 1976
Love Gun June 1977
Alive II October 1977
Rush March, 1974
Fly By Night February 1975
Caress Of Steel September 1975
2112 April 1976
All The World's A Stage September 1976
Granted, they were only 30 - 35 minutes each (or were live albums) but still.