I think you're missing the point. It's easy to set a computer to default to sleep mode, or screen saver mode, or whatever mode, after a defined period of time. The reason secured computers don't do that in 30 seconds is that under normal usage there's any number of reasons why someone using a computer may not touch it for 10 minutes, even if they are sitting right there.
That does not account at all for people getting up and leaving their station. Once someone is out of eyesight of their station, if it is not locked, for any period of time, then it is not secure. Because even at 9:59 someone just has to touch the mouse to extend the time. So one the designated user is out of sight of it, it is effectively unsecured forever. Someone waiting for that opportunity now has it.
The solution to this is to train your users to always secure the computer every time that they walk away from it, and then enforce that requirement! Which is to say, punish anyone who fails to do so. This can't be solved with software. It has to be solved with user procedure. So if you really want computer security, your people have to act to make it happen. And you have to make them do so.