See the answer words debuted by Zach Sherwin.
P | A | C | K | T | I | E | D | U | P | W | A | S | ||
A | L | A | I | A | R | L | E | N | E | I | C | E | ||
S | I | P | S | O | K | E | F | E | N | O | K | E | E | |
T | E | R | S | E | N | E | A | O | I | L | Y | |||
A | N | I | M | A | N | I | A | C | S | M | P | A | A | |
E | T | A | L | T | E | M | P | E | ||||||
P | C | S | V | E | T | R | A | D | I | I | ||||
T | H | I | R | T | Y | S | O | M | E | T | H | I | N | G |
S | I | T | A | R | M | E | N | A | K | A | ||||
U | N | I | T | S | A | D | A | M | ||||||
P | E | A | K | W | O | R | D | S | W | O | R | T | H | |
A | C | T | I | O | L | E | S | P | O | R | E | |||
C | H | I | N | C | H | I | L | L | A | I | D | E | A | |
T | O | O | D | I | D | I | O | N | N | E | E | D | ||
S | S | N | C | T | S | C | A | N | G | O | D | S |
Repeated trigrams? They must spell something! Okay … OKE ANI THI WOR CHI? Not OKE!
First letters? OAH ... oh, crud.
Middles or finals? KNHOH nuh oh.
EIIRI, that's eerie.
At least I amuse myself.
There are thousands of entries that contain repeated trigrams separated by at least once space. Custom coding can turn them all up, or a simpler RegEx search can do the same thing. I did enjoy that WORDSWORTH was featured in a wordplayish theme. It's fun to say CHINCHILLA, too, such chi-chi sounds.
Given how many possibilities there are, it'd have been great to have some extra element like the repeated letters spelling something, a revealer giving justification for these particular trigrams, or at least a couple of fresher theme answers. Maybe some DOUBLE DRIBBLED fun, or GRUESOME TWOSOMES?
Still, a smooth Monday solving experience.
ADDED NOTE: The HEADline should have been "Jeff oblivious, misses obvious theme." Glad I read Zach and ACME's for context — I would never have figured that out on my own!
Here's the RegEx that finds words that repeat the first three letters later on.