Understanding ShouldBeSearchableEvent

[MangoMarcus]

I'm just trying to get to get my head around the roles of the MarkSearchable and IndexElement jobs and whether I can use the indexRelations option (I don't think so?) and whether I need to use EVENT_SHOULD_BE_SEARCHABLE to avoid unnecessary queue jobs (not sure?)

I suppose related elements used in an index would still be considered "searchable" right?

eg. with this index both people and roles would be "searchable":

ScoutIndex::create('people')
    ->elementType(Entry::class)
    ->criteria(fn (EntryQuery $query) => $query->section('people'))
    ->transformer(function (Entry $person) {
        return [
            'id' => $person,
            'title' => $person->title,
            'role' => $person->personRole->section('roles')->one()->title,
        ];
    }),

So in my ShouldBeSearchableEvent I could do

Event::on(
    SearchableBehavior::class,
    SearchableBehavior::EVENT_SHOULD_BE_SEARCHABLE,
    function (ShouldBeSearchableEvent $event) {
        $el = $event->element;
        // Ignore elements that aren't in the searchable sections
        if (!in_array($el->section->handle, ['people', 'roles'], true)) {
            $event->shouldBeSearchable = false;
            return;
        }

        // Ignore roles unless they're related to people
        if (
            $el->section->handle === 'roles'
            && !Entry::find()->section('people')->relatedTo($el)->exists()
        ) {
            $event->shouldBeSearchable = false;
        }
    }
);

Thanks!