I'm not talking about people in your situation; I guess that wasn't clear. I'm talking about someone setting the time zone on their personal hardware. They know where they live and what their time zone is.

Besides, for your case there are easier methods, like Googling "current time in San Marcos, TX" (which Google will actually tell you the time and time zone without you needing to click on a results page; if you feel the need to, the first result has all the info you need as well). Hell, the "world clock" app on my phone tells me what I need to know when I enter in that city.