How much does smooth/standard dance technique change over time - say 1 year vs 5 years vs 10 years ?
If i look at the sites that sell dance videos, it seems that over a 10 year period
technique (or is it something else ?) must change enough to warrant a remake of some videos.
Do you think there is a difference between the speed at which smooth/standard vs rhythm/latin technique changes ? Somehow i wanna think that rhythm/latin technique might change more than smooth/standard.
What about the pace at which smooth vs standard technique change ?

What changes in technique have you observed over the last few years ?
What do you think prompts a change in technique ?

International standard technique evolves only slowly; I wouldn't even call it 'changing' as its more of a pushing the limit than revolution type of thing. Good instructional materials there may well never go out of date, though one would never be wise to depend too much on anything other than live coaches.

Smooth is a more dynamic situation: worrying about technique at all seems to go in and out of fashion every few years.