Form_validation unset 'set_rules'

[eluser]rufnex[/eluser]
Why not just validate B then A in every case?

Code:

// block B
$this->form_validation->set_rules('description', 'Description', 'required');
if ($this->form_validation->run() == TRUE) {
    // execute code for block B
}
// validation for block A
$this->form_validation->set_rules('responsible_user', 'Responsible_user', '');
if ($this->form_validation->run() == TRUE) {
    // execute code for block A
}