Beatles album with most cover versions?

Basically, it was our stage show, with some new [original] songs. Paul McCartney

"They were rather war weary during Beatles for Sale...they'd been battered like mad throughout 1964, and much of 1963. Success is a wonderful thing, but it is very, very tiring." George Martin

That weariness is apparent in the photo for the bleak record sleeve. The band members appear to be dressed for a winter funeral and stare unsmilingly at the camera. 

Tiredness is also evident in the titles of the new songs (Baby's in Black, I'm a Loser, I Don't Want to Spoil the Party, etc.)

Perhaps the most telling sign is the inclusion of six cover versions, the most on any LP.

Covers

A contemporary review in the NME described the material covered

 Numbers by Chuck Berry, Carl Perkins, Buddy Holly and the Lieber-Stoller team  .... reflect the early years of the group because they were mosly numbers that raised screams at the Cavern club in Liverpool. Nowadays, the Beatles don't get much chance to play them.

Back to the future

After Beatles For Sale The Beatles reaffirmed their commitment to releasing only original material. Except for an impromptu quotation from the traditional Maggie Mae on Let It Be, all their future recordings would be of original material. 

Whose songs did The Beatles sing? - 5-minute read