In the footer-menus-widgets.php template, from Twenty Twenty theme (by Automatic), we can find a way to code a template and call functions that uses variables to store the result of functions like has_nav_menu() or is_active_sidebar() and then use it later in the template in an if structure if ( $has_footer_menu) instead of using directly the function itself. Here is the code (i've shortened it) :

<?php
/**
 * Displays the menus and widgets at the end of the main element.
 */

$has_footer_menu = has_nav_menu( 'footer' );
$has_social_menu = has_nav_menu( 'social' );
$has_sidebar_1 = is_active_sidebar( 'sidebar-1' );
$has_sidebar_2 = is_active_sidebar( 'sidebar-2' );

if ( $has_footer_menu || $has_social_menu || $has_sidebar_1 || $has_sidebar_2 ) {
    ?>

    <div>
        <?php if ( $has_footer_menu || $has_social_menu ) { ?>
            <div class="footer-top">

                <?php if ( $has_footer_menu ) { ?>
                    <nav role="navigation">
                        <!-- some code… -->
                    </nav><!-- .site-nav -->
                <?php } ?>

                <?php if ( $has_social_menu ) { ?>
                    <nav role="navigation">
                        <!-- some code… -->
                    </nav><!-- .footer-social-wrapper -->
                <?php } ?>

            </div><!-- .footer-top -->

        <?php } ?>

        <?php if ( $has_sidebar_1 || $has_sidebar_2 ) { ?>
            <aside>

                <div>

                    <?php if ( $has_sidebar_1 ) { ?>

                        <div>
                            <?php dynamic_sidebar( 'sidebar-1' ); ?>
                        </div>

                    <?php } ?>

                    <?php if ( $has_sidebar_2 ) { ?>

                        <div>
                            <?php dynamic_sidebar( 'sidebar-2' ); ?>
                        </div>

                    <?php } ?>

                </div><!-- .footer-widgets-wrapper -->

            </aside><!-- .footer-widgets-outer-wrapper -->
        <?php } ?>

    </div>

<?php } ?>

But in Twenty Seventeen footer-widgets.php template file, we only find the functions :

<?php
if ( is_active_sidebar( 'sidebar-2' ) ||
    is_active_sidebar( 'sidebar-3' ) ) :
    ?>

    <aside class="widget-area" role="complementary" aria-label="<?php esc_attr_e( 'Footer', 'twentyseventeen' ); ?>">
        <?php
        if ( is_active_sidebar( 'sidebar-2' ) ) {
            ?>
            <div class="widget-column footer-widget-1">
                <?php dynamic_sidebar( 'sidebar-2' ); ?>
            </div>
            <?php
        }
        if ( is_active_sidebar( 'sidebar-3' ) ) {
            ?>
            <div class="widget-column footer-widget-2">
                <?php dynamic_sidebar( 'sidebar-3' ); ?>
            </div>
        <?php } ?>
    </aside><!-- .widget-area -->

<?php endif; ?>

My question is : why are they coded differently ? Does the Twenty Twenty template increase the performance of the code (decreasing the resources consumed, the page speed) ? Meaning : is it a better way of coding to store the result of a function like has_nav_menu() in a variable like in Twenty Twenty? Or is it only about maintainability and readability of code ?