Hi Mitch,
I don't think the time zone in the location master is application (CTM, heuristics, optimizer) specific.
It depends on what you have in your model version management.
Have you set it to plan in the local time zone. If No, then system will plan in UTC.
If YES, system will plan in local time zone maintaine in location master.
If you do not maintain time zone in location master, it will be considered as UTC.
Please make sure that, your resources and location have same time zone. There will be inconsistencies because of this.