Thank you everyone for all your excellent suggestions! We never knew there were so many options and it's great to hear from so many people since everyone has a different opinion. While Tintin is our third sheltie, Milou is our first GSD and it's really interesting to see the differences people suggest in training.
Our GSD Milou at almost 21 weeks is still on a nap time schedule though we've never crated the full 18 hours desired by our trainer. There is almost always someone home during the day so we'd play with her until she needed a break then crate her for bit, then back out again etc. Now that we've added Tintin to the mix we just put him on the same schedule. Since someone is home, there is no real need for them to be crated longer than a total of a couple hours during the day, but it provides an excellent mandatory nap time that our GSD still really needs.
The two of them together get a good amount of exercise. We play/walk/feed in the morning, then crate for a little bit, then 30 minutes of hard play (they chase each other into exhaustion. We start out with fetch and then they just take each others toys and run all over the yard), back in the crate for a bit, repeat multiple times until the evening when they get more play/walk/food. He barks when we leave him in his crate and when she's out of her crate but he's still in his.
Tintin can NOT be left unsupervised out of his crate at any time. He is the biggest trouble maker you can imagine. He likes to shred paper/books/toys, climbs on the coffee table, climbs on the chairs to get onto the dining room table, stands in the window, tries to climb on the kitchen counter, he'll eat anything he can find etc. He had no training as a young puppy and will do pretty much whatever he wants. His bladder control is good but not perfect, he has peed inside multiple times when he's excited but not as an intentional action. We also have cats he'd love to bother.
Milou would probably be better alone since she's had a couple months of puppy class but her control over her bladder isn't perfect (she's peed on one of our beds a handful of times, usually when she's over excited) and she'd still bother the cats. Together they'd be a terrible twosome wrecking havoc on the house and loving every minute of it.
We tried the spray bottle suggestion with Tintin before we bought the prong collar as well. Instead of a deterrent though, he quite enjoyed it and acting like he was getting a spa misting treatment as opposed to a correction for continuous, ear splitting barking.
For the prong collar, we've used it a couple times each day for 10-15 minutes while working on Tintin's training. We don't need to tug/pull/jerk it, he moderates himself well with pulling and focuses well when it's on. We've done mainly sit, down, leave it (the cat/food) etc. We also use it on his walks but would be open to using something better since so many people have great recommendations. We definitely don't like the gentle leaders since they hate them so much and the regular flat collars slip over his head so I think we might order a martingale to try.
We really can't wait to start his obedience class, when you interact with him you can tell that under all that untrained puppy behavior is a fantastic dog waiting to come out. He already loves agility exercises (a-frame and tunnel) and if his barking doesn't drive us absolutely insane, I anticipate that we'll have a lot of fun with him later on.
I forgot to add about the crating times. 18 hours for a 10 month old is way too long (unless the dog isn't housetrained). When my dogs were less than 16 weeks old, they spent a good deal of time in their crates. I actually had a "nap schedule" for them while I was not at work. Playtime only would last a half hour before they were back in their crates for another nap. Puppies need lots and lots of sleep-just like a newborn baby. This is when they grow. But for a 10 month old that is a lot of time to be in a crate. If you must crate the dog for most of the day, you must make sure it gets at least 1 hour to 2 hours of vigorous exercise daily...I'm not talking about your casual stroll. I mean running hard and really stretching those legs and using those muscles. The exercise that makes you say "He'll sleep good tonight". Is this dog housetrained? Or destructive when you are gone and left out?