What are the advantages and disadvantages of processing form data on each individual form page versus using a centralized form file in PHP?

When processing form data on each individual form page, the code for form validation and data processing is scattered across multiple files, making it harder to maintain and update. On the other hand, using a centralized form file in PHP allows for cleaner and more organized code, making it easier to manage form processing logic. However, a centralized form file may lead to longer code files and potential performance issues if not properly optimized.

// Centralized form processing file (form.php)

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process form data
    $name = $_POST["name"];
    $email = $_POST["email"];
    
    // Validate form data
    if (empty($name) || empty($email)) {
        echo "Please fill out all fields";
    } else {
        // Process the data further
        // Additional logic here
    }
}