It's a low circulation, specialty magazine. With a few exceptions, Bestumag focuses on fantasy, supernatural, and sci-fi manga. I doubt their definition of success is as lofty, and narrow, as discussion here. I've lost count of how many monthly shounen magazines Kodansha publishes. Monthly Shounen Magazine, Magazine Special, Shounen Sirius, Betsumag, and whatever replaces Rival. Only Monthly Shounen Magazine is high circulation. I am not sure any, except Betsumag, have significant bestsellers at the moment. Monthly Shomag might. Betsumag suddenly focusing on bestsellers would probably be business suicide when much higher circulation Kodansha magazines (Weekly Shomag, Morning, Monthly Shomag) are not particularly focused on cultivating "hits".