Is it a good practice to have XML document with no-namespace elements in the middle


I have an XML looking like this:

<?xml version="1.0" encoding="utf-8"?>
<n0:OrderConfirmation xmlns:n0="http://company.org/interface/MVSI"
    xmlns:ord="urn:company.com:Order:XYZ:001">
    <MessageHeader>
        <ID>001</ID>
        <CreationDateTime>2020-09-10T07:39:26.697Z</CreationDateTime>
    </MessageHeader>
    <Order>
        <OrderID>00027847</SalesOrderID>
        <Status>Confirmed</Status>
        <Items>
            <Article>
                <ArticleID>ABC001</ArticleID>
                <LineItem>000001</LineItem>
            </Article>
        </Items>
    </Order>
</n0:OrderConfirmation>

I would say a better way would be to declare a default namespace like this:

<?xml version="1.0" encoding="utf-8"?>
<n0:OrderConfirmation xmlns:n0="http://company.org/interface/MVSI"
    xmlns="urn:company.com:Order:XYZ:001">
    <MessageHeader>
        <ID>001</ID>
        <CreationDateTime>2020-09-10T07:39:26.697Z</CreationDateTime>
    </MessageHeader>
    <Order>
        <OrderID>00027847</SalesOrderID>
        <Status>Confirmed</Status>
        <Items>
            <Article>
                <ArticleID>ABC001</ArticleID>
                <LineItem>000001</LineItem>
            </Article>
        </Items>
    </Order>
</n0:OrderConfirmation>

Or more simplified: the root element could be part of the default namespace:

<?xml version="1.0" encoding="utf-8"?>
<OrderConfirmation xmlns="urn:company.com:Order:XYZ:001">
    <MessageHeader>
        <ID>001</ID>
        <CreationDateTime>2020-09-10T07:39:26.697Z</CreationDateTime>
    </MessageHeader>
    <Order>
        <OrderID>00027847</SalesOrderID>
        <Status>Confirmed</Status>
        <Items>
            <Article>
                <ArticleID>ABC001</ArticleID>
                <LineItem>000001</LineItem>
            </Article>
        </Items>
    </Order>
<OrderConfirmation>

because the n0 namespace value is global to the system and for all XML documents generated by the system.

I am wondering if this is a good practice in XML to let the middle elements in the “no-namespace” and alternatively to declare a namespace that is never used.