I’m checking the doc for add_rewrite_rule at https://developer.wordpress.org/reference/features/add_rewrite_rule/, based mostly on its description, it stated "Any value in the $after parameter that isn’t ‘bottom’ will result in the rule being placed at the top of the rewrite rules."
If I perceive accurately, the next code:
add_rewrite_rule('/rule1/', 'index.php?rule1', 'high');
add_rewrite_rule('/rule2/', 'index.php?rule2', 'high');
add_rewrite_rule('/rule3/', 'index.php?rule3', 'high');
will trigger the rule precedence of:
rule3(most excessive)
rule2(second excessive)
rule1
Is that appropriate?