Has single whip evolved?

Actually, Chen came first.

Yes, single whip has evolved.
And it has devolved.

It’s a bit schizophrenic.

Bruce tries to recreate the “Old Yang” style.
(But it’s a bit like trying to figure out how a dinosaur walked. Did T-Rex use its tail as a weapon or to walk or as a brain? No language then, no poems, no songs, no classics, no drawings, no photos, no video, no Flipper-vision, no internet, just bones.)

There are 3 main functions of Tai Chi as I know it today.
1. martial applications,
2. neigong internal and
3. meditation

Bruce probably correctly concludes that the originator of Yang style (Yang Lu-chan) never viewed the Form as meditative–strictly martial (and neigong internally).
I can’t figure out where grandson Yang Chengfu fits into this. Bruce certainly uses his principles of neigong.)

Wu style, however, is grounded in meditation.
The final part of Single Whip is about meditation.
The main point is to return to stillness within the short form (from Bruce’s “Tai Chi Mastery Program”).
In Bruce’s TCMP Single Whip is broken down into 5 parts.
(not into 6 mini-parts here in his “Old Style” instruction.
Hence my characterization of schizoid.)

In the Chen Style and probably in the “Old Style,”
wuji was only expressed at the start and end of the form.

Bruce, however, offers the first 5 movements of the Yang Long Form as a mini-form where Single Whip concludes Peng and Grasp the Sparrow’s Tail. So, of course there has to be a little wuji in Single Whip–that’s the ‘settling into the left’ Which puts meditation into the
“Old Yang” form.
in the Wu Short Form Bruce even recommends holding Single Whip at this transition for 5 minutes–clear meditation.

No other “New Yang” form that I know of does this;
not even grandson Yangchengfu.

Furthermore, Chen Master Ren GuangYi in the Lao Jia Yi Lu form of Chen, includes no wuji-like transition in the Chen form (in his “Flipper-Vision” DVD there are 19 frames, 5 leg weight shifts, but no double-weighted transition. All continuous internal neigong. (I know very little about Chen Style.)

My conclusion: Yang Style Tai Chi is also meditative.

(Side note: Single Whip usually precedes Cloud Hands and comes after Cloud Hands in the Yang Style–
like Quotation marks around Cloud Hands–
sorta a regrouping of energy and ramping up the revs of Qi–note that in a quotation mark (“) there is a still space–ha, ha.)

I’ll continue to start my Yang with the 4 part Wu commencement
(not just raise and lower hands, but also Peng-up Ji-out, Lui-in and An-down) because I like it.)

Likewise, I’m now putting in the ‘settling’ into Single Whip because I like to meditate there.

Kinda like religion:
Most Christians don’t keep the Sabbath on Saturday like the original Jewish “Old Style” religion–but then some New Testament people keep it Old–a de-volvement.

It doesn’t seem to harm the Spirit of the practice.
The difference highlights the function of a day of worship and rest.

By the way, one “New Style” Yangist calls the final Yang style hand position:
“A Beautiful Lady’s Hand.”
(Master Tchoung Ta-Tchen)

Just my humble opinions.