I've always been fond of time travel stories, about people travelling into the past or into the present. There was one year (2012) in which there were almost always a drama airing with time travel: Faith, Rooftop Prince, Queen In Hyun's Man, Time Slip Dr. Jin and Operation Proposal.5 dramas with this topic aired in the span of a year.

Last year dramas with vampires started one after the other: Blood, Orange Marmalade and Scholar Who Walks the Night. Also, two dramas started airing at the same month with characters who have multiple personalities: Kill Me, Heal Me and Hyde, Jekyll, Me.

Yesterday I created a list of remakes I knew about and found out that in 2012 there were 4 dramas that were remakes of Japanese dramas. Every now and then there is one, but 4 seems to be too many.

Have you ever encountered with a similar situation while watching dramas?

What is your opinion about this? Are they coincidencies or do TV channels really focus in the same topic as their peers?
I'm pretty sure it depends on trend. If something is successful in Japan, it is assumed that it will be successful in Korea, too. If one network announces a certain themed drama that soubds trendy, then other networks will follow with similarly themed dramas and each will try to outdo the other in casting, budget and marketing.
Yeah it's certainly not a coincidence. It seems like when a drama with a certain theme does well, several dramas with similar themes are always sure to follow. They just follow the trends. For instance, it seems like the popular trend this year in korea is doctors, lawyers, and sageuks. Remakes on the other hand always seem to be trendy, so four in one year? Certainly not surprising.