You can always ask a CM by those machines if they can exchange for the 10:15 show for you. That's what I sometimes do, and did earlier this month. They hand-wrote them, but they did it. Not a guarantee they will always do this, but it can't hurt to ask, right?
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Earlier this month, I saw the new shows in one night, on more than one occasion.
First time, I waited in Tomorrowland for 8:50 PTN to pass (but wasn't really watching) and then got a great spot in the Hub for the fireworks. Then, after that, I booked it out of DL and to DCA for WOC. Made it two minutes before they closed to gates. After WOC, I went back to
Disneyland and watched PTN from a spot by Small World. I was solo for this one.
The other time, I kind of hung out in the penny arcade on MS, and then hopped into the parade crowd when the Frozen Float was coming. Then, after the final float, everyone flooded the street, and watched the show. I had my 7 year old sister with me, and we were able to get to DCA with several minutes to spare, and a spot on a rail for WOC.
I've also watched the fireworks from Town Square, on another night we saw the 9:00 WOC first. View wasn't great, and crowding wasn't better like you'd think it should be.
Taking everything into account, I'd HIGHLY recommend watching from MS by the Penny arcade or South. The projections are awesome, and the show is so much better from there. Especially seeing as you are solo, the added effects you see from this spot are worth the extra few hundred feet of walking through crowds, and it doesn't add all that much time to your egress.