PHP-FPM and httpd.conf settings question

Hi Cpanelers, I've heard that there is a special arithmetic to respect when configuring a couple of things on httpd.conf and PHP FPM. I've heard that there must be a ration of an integer between Max request workers in httpdconf and the max children of the PHP-FPM pool option in the multiphp manager of cpanel. True ? Further more, admiting I put max request workers to 256 in httpd.conf and I have 10 websites on the server. 2 big and 8 average Is there a good repartition of maxchildren, process idle time and max requests in php FPM for each ? thanks.