> Did your elementary school teacher make it clear whether you should pronounce the middle two t's in gotten as a glottal or a held stop?

Yes

> What do you think of that advice today?

It is a small part of my English enunciation.

> How might it vary depending on where in the anglophone world you live, and your age?

Significantly.

But I did not author a critique regarding English prose and the nature of prevalent sentence structures therein.