I read I should increase gc_maxlifetime in php.ini to the same large value (weeks) as the one I'm telling Zend_Session::rememberMe(). Is this good practice? Is there a reason not to increase gc_maxlifetime to more than half an hour or so?
it is good practice. if you have many (thousands) site users - you can code custom session handler. for example, to support different directory structure.
like /sessiondir/0/1/5/0152837462938587.sess to minimize server load while reading dir with many files