If you go back and look at some of the books prior to the reboot, some of them seemed to anticipate that they were coming to an end (such as the "soft" reboot of WW and the killing of Alan Scott in JSA) while others seemed to just end abruptly. Others are kind of toss ups. Grounded reads like someone out of ideas who is just killing time knowing they are coming to an end. But the Reign of the Doomsdays reads like it was meant to be a regular storyline. I have the last Power Girl issue before the reboot and it clearly ended in the middle of a storyline that was meant to keep going. I can only guess there are a number of titles for which this is true. The whole suggests this was dropped in a lot of people's laps without warning.