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!
I think you are supposed to do it until white milky stuff comes out, but I never had a bitter cucumber, and I have even grown them too big and old and yellowing before picking, like the size of a big fat baseball bat. I just peel and scoop the seeds out of the cucumber just like it was any other melon and the flesh tastes just fine.
Best Answer
You need a sharper knife. With a dull knife, you'll have trouble getting through the skin, and end up tearing and smashing, releasing a lot of juice. With a sharp knife, you'll get through the skin cleanly and leave the tomatoes much more intact.
Serrated knives are another common option: they get through the skin very easily. A dull serrated knife will tear the flesh up a lot, though, so you still do need a reasonably sharp blade, and while a cheap bread knife or steak knife might be better than nothing, it's not ideal. The best ones are probably the ones actually marketed as tomato knives: they're sharp, not too thick, and have a serration pattern that's meant for this.
If you're forced to make do with an inadequate knife, you can break the skin with the tip, then extend that with the blade and slice from there. If the knife is so dull that it still makes a mess, you might be out of luck. This is pretty time-consuming, though, so I wouldn't suggest it as an everyday method for a lot of slices.
Freezing, as you suggested, doesn't sound like a great idea. If you freeze tomatoes thoroughly enough to make them firmer and easier to chop, then you'll have formed a lot of ice, and once they thaw, they'll tend to disintegrate and release all that juice. It won't affect the flavor, but it's kind of pointless, since if you're willing to mess up the texture that much, you might as well just hack it up whatever messy way you like.