Readers have to struggle through sentences with jammed middles. The problem is not just too much information in too little space, but also delaying what the reader needs to know.
Sometimes the jam happens between the subject and the verb, the anchors of a sentence, as in this example:
In 1668, the Earl of Clarendon fell, and Pratt, whose reputation had been irrevocably linked to his patron’s since the unfortunate timing of the completion of Clarendon House in Piccadilly at the very moment when many Londoners lost all their worldly goods (and their property) in the Great Fire, took retirement.
Forty words intrude between the subject “Pratt” and the verb “took.” Easily solved with two sentences, and nothing separating subject and verb:
Pratt’s reputation had been irrevocably linked to his patron’s since the unfortunate timing of the completion of Clarendon House in Piccadilly, at the very moment when many Londoners lost all their worldly goods (and their property) in the Great Fire. In 1668, the Earl of Clarendon fell, and Pratt took retirement.
Sometimes attribution and dependent clauses get in the way:
Bats are mammals, but the species now afflicted by white-nose syndrome are cave-hibernating bats, and when the bats lapse into their hibernation torpor, said David S. Blehert, a microbiologist with the United States Geological Survey in Madison, Wis., their core body temperature drops down to just a couple of degrees above cave conditions, as low as 44 degrees.
This sentence has three independent clauses, with a dependent clause (“and when…torpor”) plus a 14-word attribution in the middle. The reader can’t tell if Dr. Blehert said all three independent clauses or just the third one. Better to introduce the speaker and then let him talk.
Sometimes extraneous facts slow things down and clutter up the middle, as in this example:
Dorothy (played by Judy Garland in the 1939 movie), backed up by the Tin Man (Jack Haley) and the Scarecrow (Ray Bolger), slaps the paw of the Cowardly Lion (Bert Lahr) for frightening her dog Toto and says, ‘It’s bad enough picking on a straw man, but when you go around picking on poor little dogs….’
The inserted movie-star names keep delaying the action, and complicating the list. They add nothing to the readers’ understanding.
Sometimes parenthetical asides can make readers lose the beginning of a thought by the time they get to the end of the thought:
I made some notes on it, not because it reminded me of anything in Chaucer – the research I was in fact beginning – nor as a seed for the major research project it would become – it was years before I recognized that – but because I did not want to lose the details of this image.
Those four dashes create a feeling of hesitation and a tone of uncertainty.
And sometimes the middle gets cluttered with flashy junk:
Editors could still accommodate a degree of financial risk in their acquiring, and so it came to be that Reif Larsen, a 28-year-old graduate of Brown and Columbia, with his explorer’s name and brief history promoting a Botswanan marimba band, ignited the spending impulse of the publishing world, producing such a fire that he extracted a reported $1 million for his first novel, ‘The Selected Works of T. S. Spivet,’ a book in which each page seems a vitrine constructed to exhibit the author’s discursive, magpie imagination.
This reviewer was evidently trying to compete with “the author’s discursive, magpie imagination,” while her editors snoozed.
I would not call any of these sentences bad. None of the jam-up in the middles is accidental, but they’re hard to read. In writing, we always have to balance readability against voice.