The Beatles wrote a lot of songs to order and under pressure. Some of their best songs in fact, so I don't see why that's important.
In any case the pressure may have been exaggerated.The following interesting site says
"The “pressure” was probably due to this being an attempt at writing their next single, which both John and Paul admitted in a 1966 interview that the composition was "forced." However, when asked later that year to re-confirm this, they denied it
And here's another quote from the same site saying the Beatles preferred Day Tripper :
'George Martin explained at the time: “After we gave both titles to EMI, the boys decided that they preferred ‘Day Tripper,’ but both sides are extremely good and worth a lot of plays. As far as EMI’s official policy is concerned, there is no A-side, and both will be promoted equally.” '
This is the opposite opinion to yours when you say "I've also read that the Beatles preferred "We Can Work It Out" over "Day Tripper".
I'll take George Martin's point of view.