XQuery/Xpath optimization: query different parts of the same document

Let's say we have XML files with different parts: title, description, text, note.

<book>
    <title>Some title</title>
    <description>Some description</description>
    <text>Some texte</text>
    <note>Some note</note>
</book>

Let's say we want to be able to query in these different parts. This can be done by different approaches.

For exemple, we want to query only in title and note.

approach 1 (basic verbose version)

for $result in (
    collection("path_to_my_collection")//title[ft:query(., "'word_to_search'")]
    , 
    collection("path_to_my_collection")//note[ft:query(., "'word_to_search'")]
    ) 

approach 2 (take this one from here)

for $result in collection("path_to_my_collection")//(title | note)[ft:query(., "'word_to_search'")]

approach 3 (this one seems to be advised by the documentation )

let $docs_and_parts :=
    for $parts in (collection("path_to_my_collection")//title, collection("path_to_my_collection")//note) 
    return 
        $parts
        
for $result in $docs_and_parts[ft:query(., "'word_to_search'")]

After reading the XQuery optimization technic, I'm wondering which one of these approaches is more efficient/fast for execution in large collections with many (more than 100) files?