IIRC when Len was moaning about Brendans Jive, didnt Brendan mention about it containing the required amount of time dancing. Also IIRC he said something along the lines on ITT, that he timed it specificly to have (again i only remember roughly) the required one minute of dance. This seems to suggest under the new rules they ahve a minimum amount of time for the acyual dance, but have a maximum amount of time they can "faf" about in the routine.
As for the so called "faffing about" i really think it depends on the dance. If it adds to the story and choreography of the dance, and doesnt seem too long, then i have no problem with it. Take Patsys and Robins Jive, alot of people said they took to long to start. But for me i didnt mind the time it took to start, as i think it added to the story and fitted very well with the theme and the story. On the other hand Felicity and Voncent walking down the stairs the other week, for me did nothing for the choreography or story, and stuck out like a sore thumb as a way to reduce the dancing to help Felicity.