Over my programming career I formed a habit to introduce a flag variable that indicates that the first comparison has occured, just like Msft does in its linq Max() extension method implementation

public static int Max(this IEnumerable<int> source)
{
    if (source == null)
    {
        throw Error.ArgumentNull("source");
    }
    int num = 0;
    bool flag = false;
    foreach (int num2 in source)
    {
        if (flag)
        {
            if (num2 > num)
            {
                num = num2;
            }
        }
        else
        {
            num = num2;
            flag = true;
        }
    }
    if (!flag)
    {
        throw Error.NoElements();
    }
    return num;
}

However I have met some heretics lately, who implement this by just starting with the first element and assigning it to result, and oh no - it turned out that STL and Java authors have preferred the latter method.

Java:

public static <T extends Object & Comparable<? super T>> T max(Collection<? extends T> coll) {
Iterator<? extends T> i = coll.iterator();
T candidate = i.next();

    while (i.hasNext()) {
    T next = i.next();
    if (next.compareTo(candidate) > 0)
    candidate = next;
}
return candidate;
}

STL:

template<class _FwdIt> inline
_FwdIt _Max_element(_FwdIt _First, _FwdIt _Last)
{   // find largest element, using operator<
_FwdIt _Found = _First;
if (_First != _Last)
    for (; ++_First != _Last; )
        if (_DEBUG_LT(*_Found, *_First))
            _Found = _First;
return (_Found);
}

Are there any preferences between one method or another? Are there any historical reasons for this? Is one method more dangerous than another?