The precarity of freelancers aside, this is a slight improvement on a system in which every series is either a great success that runs for a hundred issues or a failure that fizzles after seven. In this system your comic can be a nice, tidy 6-issue story that sold so-so but became a cult classic.
I keep telling people this and no one believes me: at least at DC, there is no such thing as “ongoings” and “minis” anymore. There hasn’t been for about 5 years now. Every single set of 6 issues is an audition to the readers for more.