Well the max half-life is 24 hrs, so any hits on a 0 def country would I guess just have a 24 hr half-life. That's not that different from 18 hours really.

But when you say "come back again and do it a few days later," that's kind of what this change is put in to eliminate. For example, say a guy abandoned his country and you hit him 6x. You can't come back on the next day at just the right time and hit 6 more times. Because attacking at 20:58 will give basically the same returns as hitting at 20:55 which will give basically the same returns as 20:45 etc etc etc.