Let's see....
First, we have to guess at the time that Edge would want to take off for his daughter. Since we have no idea exactly what the deal was, let's just say that she needed chemo for leukemia, since that is the prevalent thought. If she has Acute Lymphocytic Leukemia, which is the most common leukemia in kids, consolidation chemotherapy takes 4-8 months. Gee, there's 8 months right there.
But instead, let's be stingy and assume that she rocked it out in 4 months. This chemo, by the way, isn't like every day of the entire time period, so Edge can be there for the chemo and still globetrot to London for recording, New Orleans for charity work, etc., and still be there for chemo and not warrant fans calling him a "poor dad."
So yes, let's be stingy and say that she rocked it out in only 4 months. So, Leg 4 is midway through and Edge says, "Hey guys, I need 4 months off. Let's see if we can ge the tour going again four months from now." Okay, so lay off the 200 people who are in the crew, design, management, etc. of the tour. Since most of these people have been with you for at least a decade, if not more, you probably want to make sure that they can be with you when you restart the tour. So, start the task of finding out when each of these 200 or so people can come back to your tour. I'll guarantee that a good chunk of the lot can't just hop along and come back right at your 4 month tentative start date. You've probably got to give a month, or even a couple, in order to get all the important people (who don't just work on U2 tours, mind you).
Okay, so now we're at 4 + X months. Now, coordinate the trucks, planes, storage, etc., for all of the tour material. Find out when you can get all that. Also, find out when you can get transportation and lodging for your 200-person crew. Oh, and find out when your stadium dates are available. It's not like you can just pick a few dates here and there, either----you need to pick a block of dates in
several different countries where you'll have availabilities
all within a few days & weeks of each other that'll
also coordinate with the lodging, transportation, etc., logistics that you're working on.
Jeez, an extra few months on top of the already 4 months seems like a pretty short time to figure all that stuff out.
Should we try figuring it out if Edge's daughter needed the whole 8 months of chemo...?
Moral of the story: A 9 month delay is MORE than feasible, especially if you tack on the bit of personal time that the break was intended for anyway.
Honestly, it's kind of lame that the argument has gone from "U2 need to spruce up Leg 5 because playing the same stuff from 2 years ago will be lame"....to...."U2 is lame for making these poor Aussies, etc., wait 9 months for the same tour, when I think they just wanted some time off to goof around."
Ultimately, whether the band played the same exact 24 songs 9 months ago or now, it'll be the same exact show either way. Sure, I'd like to see some new stuff in there---absolutely. But the effect of the setlist on the people going to see U2 live will be the same whether U2 hadn't been to their country in a decade and they saw them in March, or U2 hadn't been to their country in a decade and they saw them in November.