Am I the only one that likes how they do interlude's with their single promotions rather than just doing two songs like other groups? I mean first Play Girlz and now Let's do it. It's really smart IMO.
I'm a bit confused with what you mean by interlude?
They've only had 4 singles so far which means just half have had some kinda intro type songs in them.
The interlude thing I think has more to do with their 'rookie' status, like how f(x) was doing that intro dance for Lachata.
AFAIK, intro dances don't have anything to do with 'rookie' status. After School aren't really considered rookies anymore either, it's already been a year since their debut. Special performances such as intro dances, teaser clips before perfs, doing two songs, doing the full song of a really long song, etc. are usually limited to only comeback perfs, goodbye stages, and special shows, unless they changed it in recent years. Some performers even record their same song twice in different outfits to give a cool effect (BEG, Kara in recent memory). In the end, I think it all just depends on the companies budget to promote and the artist. (As for T-ara on M! Countdown, M-net is their label so the company can do whatever they want on their own show

) For example, Rain is on his comeback right now and is doing two almost-4 minute songs

That can't be cheap.
On a side note, LDI! is now my Nike+ power song
