Optimal shape to cut apples for apple pie I have always enjoyed a slice of apple pie... in the morning... afternoon... and after dinner. Or anytime actually. And as such, I had to learn to bake my own apple pie to satisfy my deep affinity with them. 

When I bake apple pies, I make sure to use the best apples I can find. I typically always go for Honey Crisp for its sweetness/slight tang and firmness to stand up to the baking. For the longest time, I have been cutting the apple by first peeling the apple, cutting the apple into 4 pieces down the middle and coring each piece. I then cut the apple pieces into slices in the shape of the apple so I get crescent shaped slices. 

I have alway had success with my pie and I'm actually quite proud of it. Recently however, I shared a slice with one of my roommates. He enjoyed it but he made a passing comment about how strange it was that I cut the apple in crescent slices(that ungrate... haha jk). That bruised my ego a bit.

So now I want know how other people cut their apples when they bake their apple pie? 
And has anyone tried the crescent shaped method and a different method and found that one worked better?
I've eaten plenty of apple pies with crescent slices. Nothing wrong with it at all. If you don't have any special tools, it's probably the best way to get slices that are the full length of the apple. It's probably what I'd do if I made a pie tonight.

A lot of people probably slice differently, though. In particular, if you have a corer (which doesn't also slice) you can peel, core, and halve the apple, then cut thin slices perpendicular to where the core was. It's easier to get thin slices this way, since you're making parallel vertical cuts. Of course, it's a pain to core a whole or half apple without a special tool. 

Perhaps some people out there, especially if using very large apples, peel, quarter, core, and then slice, getting quarter-circle slices. Some people prefer small pieces; they might use a corer/slicer to get get 8 wedges, then slice those further.

People who make a lot of apple pies might have a device like this peeler/corer/slicer. It does all three simultaneously, rotating the apple to peel it, pulling it across the corer, and slicing in a spiral as the apple rotates and moves horizontally. Theoretically you end up with a peeled, cored apple that's thinly spiral-sliced the whole way through. At that point you can just cut it straight down the middle, and end up with half-circle slices.

I expect your friend was simply used to one of those methods. But any kind of apple pie you can think of is being made out there. Slice them how you like!