Plesk Automation :: System Or Service Template Defaults For PHP

Is there a way to set default PHP settings so they apply by default to all websites' custom php.ini file, or even server-wide or system-wide? For example, the timezone? I am using custom builds of PHP 5.5 and 5.6, per the PPA docs, but I found that, contrary to some Plesk (not PPA) documentation, /etc/php.ini is not used. It looks like a set of PHP settings are generated into a php.ini for the vhost, and I can set "Additional Directives" for each website but would prefer to set a system default. For instance, on recent PHP versions not having a timezone set generates a warning in the logs on every PHP execution. I'd also like to enable opcache since we're using FastCGI. So from where does PHP generate the vhost's php.ini?

As an aside, adding an "Additional Directives" entry with this unquoted generated an error and no directives were saved:

date.timezone=America/Chicago
Instead, I had to quote it:
date.timezone="America/Chicago"