How can I get every nth item from a List<T>?

return list.Where((x, i) => i % nStep == 0);

I know it's "old school," but why not just use a for loop with stepping = n?

Sounds like

IEnumerator<T> GetNth<T>(List<T> list, int n) {
  for (int i=0; i<list.Count; i+=n)
    yield return list[i]
}

would do the trick. I do not see the need to use Linq or a lambda expressions.

EDIT:

Make it

public static class MyListExtensions {
  public static IEnumerable<T> GetNth<T>(this List<T> list, int n) {
    for (int i=0; i<list.Count; i+=n)
      yield return list[i];
  }
}

and you write in a LINQish way

from var element in MyList.GetNth(10) select element;

2nd Edit:

To make it even more LINQish

from var i in Range(0, ((myList.Length-1)/n)+1) select list[n*i];