Why work on the standard B-flat fingering?

On one of the flute discussion groups, the age-old question came up this week, of

"Which B-flat fingering should be taught to students first?"

And:

Even though professional flutists use B-flat thumb key as much as possible, why do teachers like Trevor Wye suggest in their flute practice books to continuously rotate the practice of all three B-flat fingerings?

(And if you don't know this topic well, just click on the above jpeg of three B-flat fingerings to have a look at the three B-flats).

Well, the simple answer is that the standard B-flat fingering and the side-lever fingering both use the same right index finger and a flutist needs to gain skill in using these two fingerings.
As examples, here are some absolutely terrific B-flat fingering-twizzler-type music excerpts that I found today for the flute teacher's answer and a good flutey play through!

They are the B-flat godzillas and boy are they good ones. :>)

Repetoire & Etudes for B-flat Savvy Flutists in pdf (780 kb)

Here's another page of Widor's Suite for Flute, showing all the B-flat finger suggestions (try them out and see how they work for you).
The Widor samples show the symbols that can be used to mark flute parts too.

In general: For the flutist who prefers Briccialdi's B-flat thumb key, and who attempts to use thumb sliding for these particular excerpts, you'll find it gets tricky to impossible to play these works at fast tempi.

Thumb sliding is less reliable at fast tempi than open B-flat thumb key switches. Thumb key switches are made when the thumb is open already for a C, C# or G3, and then descends onto the alternate thumb key.

So thumb key switches must be practiced by the intermediate flutist.

And naturally, the weakest fingering, the 1+1 or "long" B-flat fingering, must be practiced the most diligently, especially in preparation for these tricky passages that crop up from time to time with F-sharps and G-flats in the topmost register, and those fairly frequent A# to B-natural chromatic sequences and arpeggios.

Eventually the intermediate flute student needs to be equally practiced in all three B-flat fingerings and cycle between the three, in daily practice, in preparation for more advanced repertoire.

Occasionally we see in our studios a flute student who, after several years of only playing thumb B-flats, has to back-track and re-learn the contrary finger motions required for the standard B-flat fingering (1+1).

This can be disheartening for them, as they might think they are "advanced" enough for fast etudes and repertoire.

To avoid this future problem, it's smart to teach the use of the easy Briccialdi B-flat thumb key only once the student has lightness, balance and facility with the standard fingering.

Also, I located a good general article, suitable for all levels of flute students and teachers "Bb fingering choices" article in pdf by Patricia Surman, ( look for the third articles down at this link),  with some additional short musical examples such as the use of the F to B-flat balance aid of the standard fingering:

Both pdfs are good for printing out for the music stand.
Very fun to get into this topic! Comments welcome!

More:
Bb fingering choices for Prokofiev:
Peter and the Wolf Fingerings

Prokofiev Sonata for Flute and Piano fingerings for triplet runs

Free practice pages: scroll down to links when you arrive.
Free pdfs of scales and scales in thirds with thumb switches marked "o and +" (off and on Bb-thumb)

Best, Jen