_maybe_update_core()
Function: Determines whether core should be updated.
Source: wp-includes/update.php:927
_maybe_update_plugins()
Function: Checks the last time plugins were run before checking plugin versions.
Source: wp-includes/update.php:952
_maybe_update_themes()
Function: Checks themes versions only after a duration of time.
Source: wp-includes/update.php:973