What's the best way of turning over multiple items in the oven? For example when baking french fries or meat balls I turn them over halfway but it can be a bit tedious to rotate one at a time. Has anyone had luck just shaking the pan or is it really supposed to be a 180 degree flip?
Yes, it is supposed to be a 180 degree flip, you want both sides to be heated evenly.
If you are using a flat or low-rimmed baking sheet, and have a second one the same size: oil the second sheet with only a very thin layer of oil. Take the first sheet outside, cover with the first. Grasp at the two sides, flip both sheets with the food sandwiched between them. Bake in the second sheet (which is now on the bottom).
Of course, this has its downsides too. You cannot use baking sheets with too high a rim (else the food will slide inside too much), you have a second sheet to clean, and there is the danger of burning yourself while you wave a hot baking sheet around. But especially for large amounts of food, or multiple batches which are done in two sheets anyway, it might be less hassle than turning with a spatula.
The most effective method is simply not to flip the items. There are a couple of ways this can be possible:
If you cannot avoid having to flip, a large spatula that can flip a lot of items at a time can help, assuming the items are not too fragile.
Again, if the food is not fragile, you can shake the tray, allowing the items to turn randomly. Doing this several times throughout the cooking period will allow the items to cook fairly evenly overall.
If you have fragile items (like a meatball) and feel you must flip them, patience and a good set of tongs will be your friend.