And what formats would those be? In Buffalo, there's not one station that relies on cold segues. Sure, 97 Rock and Jack FM may roll one per hour (maybe intentionally, maybe because somebody missed a voice rack slot) but that's it. If and when these stations do roll a cold seg, it's not one of those "Oh wow" segues (Pink Floyd's "Money" to the Beatles' "Tax Man") that might have impressed a few listeners back in the day (and these days are inconsequential), but two hits that most listeners recognize. Most often played between the hits is a bumper/sweeper/jingle/voice tracked rollover, in every format, from WYRK to WBLK. Yesterday while listening to Kiss, I heard a power recurrent ballad, female roll into an uptempo current, male. Between the two was an imaging bumper. No big deal. They were hits. It worked.
I did not say "cold" segues... just segues. There can be a sweeper, "live" name/calls or something brief between songs but there is still a transition that follows a mood or feel.
Djs at clubs get this. They know they have to do mood variations both for variety and to get people to return to tables and order drinks. They don't play all one kind of song, but they know how to do the blend so that the mode shifts... not crashes.
A well programmed station tries to make each segue, each sweep, each hour have a consistent balance and enough tempo and style variety to bear the trademark of the station sound.
Of course, if you don't recognize the need for that, then that may be part of what radio has lost. A computer can't program a station, and thinking it can without intervention makes for just what I mentioned previously... a playlist on "shuffle". There are millions of ways of combining a 300 song typical AC playlist... but nowhere near as many that have the right segues and perfectly balanced sweeps.