"Doctor Robert"

"Day or night" in the line "Day or night, he'll be there any time at all, Doctor Robert" in "Doctor Robert" is a temporal merism.

To some degree, the structure of the song even evinces the statement "he'll be there any time at all" since the name "Doctor Robert" (or occasionally "Bob Robert") appears multiple times throughout each verse (at the end of both of the first two lines, in the middle of the verse, and at the end), suggesting a sort of ubiquity.

"Eleanor Rigby"

The repeated line "I look at all the lonely people" in "Eleanor Rigby" is sung to a phrase something like:

Admittedly, I'm not super confident about the last two notes in each part.

The phrase "all the lonely people" is sung to pitches spanning more than an octave (A down to G and F# down to E), and this breadth provides a musical sense of that "all."  That there's a second vocal part here (in contrast to the single vocal in the verses) also gives a sense of that multitude.

"Taxman"

I listened to Revolver yester-day and noticed a few small features.  Even before I started listening to the album, I realized that the inclusion of the "one two three four" count-off in "Taxman" has a sort of double meaning in light of the subject of the song:  the musicians are counting the beats, but the taxman is counting money.

"Penny Lane"

Lately, I've been listening to the McCartney: A Life in Lyrics podcast.  Yester-day, I listened to the episode on "Penny Lane" and noticed a small feature in the song:  the line "It's a clean machine" exhibits internal rhyme, and this provides a sense of that orderliness.