Switch to Glide

I think most of us agree on these two things..

1. At slow tempos, the slide clearly needs to stop on every note. Alessi once said, "I want to see the rhythm in your slide."
2. At very fast tempos, your slide can't really stop on every note. The classic example of this, I suppose, is the excerpt from William Tell.

I have heard of teachers advising students to practice the William Tell excerpt in an unusual way: even when you play it slowly, don't stop and start with the slide. Instead 'catch' the note as the slide goes by without stopping.

Even though I glide at fast tempos, I find this 'slow glide' practice technique to be awkward. (maybe I'm doing it wrong).

Lately, in my warm-up, I've been playing a lot more chromatic scales. I always start playing slowly over a limited range. Something like this:

Then I extend range and increase speed. I like to end up going full-speed with double tonguing.

Of course, at some point, I switch to the glide approach.

Anybody with a high speed camera? It would be interesting to film top players as they play fast then slow the film down to see what they are really doing with their slides.

Hmm, doctoral dissertation idea?

It will need a lofty title...

"The High-Speed Video Analysis of a Select Group of Professional Trombonists to Ascertain the Transition from the 'Stopped Slide' model of technique to the 'Steady Slide' model at Increasing Tempi"

zzzzzzz