You could say it's broad since "4k" is generic to multiple different specifications close to 4k horizontal pixels. But when you refer to 4k, it's about the dominant 4k standard which is uhd, 16:9, 3840x2160. By these standards, 12k = 11520x6480. 3x4k would be 48:9 and there really isn't any standard with that aspect ratio. The widest standard is ultra wide 21:9 or cinemascaope which is hardly different at 21.51:9. The only time you are seeing this odd ratio of 48:9 is with computers in eyefinity/surround but other than games with those res, there is no other media that uses this format. 3x 4k may have 12k horizontal but you wouldn't call 3x 1080p, 6k. I could name off smaller monitors in eyefinity/surround and none of them are named...