Have you ever noticed that people tend to list in threes?
Listen to the next lists people rattle off, usually to conclude with or summarise. Advertisers, TV presenters and the more articulate victims of vox pop interviews are among the chief users of the triplet. But normal people also incline to trebling their conclusions, often ending their statements with a list of three issues, observations or comments:
"Looking for a healthy way to fill up the kid’s lunchbox? Well Fast Ed has the answer. His DIY muesli bars are nutritious, low GI and absolutely delicious!"
- Better Homes and Gardens
"...I just grew up listening to Jimmy Barnes, going to Jimmy Barnes concerts, I'm just a real fan, I really like his music."
- Mark Schwartzer (Socceroo) on why he likes his favourite artist.
"A year and a bit ago, I was flabby, over-weight and (it grieves me to say so) deeply unattractive."
- Stephen Fry on 'A Bit of Fry and Laurie".
"It's like a shammy, it's like a towel, it's like a sponge."
- The Sham Wom Infomercial.
Tripleteers seem to find that two items are simply not enough to ram home the core of their conveyance and four too many. Sounds reasonable. But as a believer in the theory that almost everything everyone ever says is formulaic, sheepishly copied verbatim from the status quo, it is more likely they use triplets to list and summarise because everyone else in their sphere of influence does the same.
For the more sub-consciously discerning conveyor of triplets, the appeal may include an appreciation for the aesthetics of speaking - the accidentally poetic aspects that all languages share in some form. The triplet offers a wonderful rhythm and the poetic finale' of a beginning, middle and end. The rhythmic form of the triplet is often comparable to the anapaest metre of the limmerick: didada, didada, didaa...
The rational tripleteer is probably aware of the audience's inability to retain/comprehend more than three pieces of information at a time.
There may also be a cognate relation between tripleting and the tripartite motto and the hendiatris, eg:
"Postera Crescam Laude", University of Melbourne
"Veni, vidi, vici", Julius Ceasar
"Liberty, Egality, Fraternity",
French National Motto
...and also with historic phrases:
"Father, Son and Holy Ghost."
"Hook, line and sinker."
"The truth, the whole truth and nothing but the truth."
...and even modern phrases:
"Sex, drugs and rock 'n roll."
"Slip, slop, slap."
"Location, location, location."
However, where the hendiatris is formal, designed and planned for, the triplet is informal, incidental and spontaneous. The triplet reveals a sub-conscious inclination to declare a threesome, driven by aesthetics, reason or because everybody else does.