You didn't mention where in central Texas you are located, but I'll just assume you have weather similar to that of Austin, TX.
In 2014, Austin got 36 inches of rain and half of the total rainfall for the entire year came in just seven days of the year. Two thirds of the rain for the year fell in about 11 days. As a comparison, where I'm at in Indiana, we got about the same amount of rain for the year (40 inches), but to account for 2/3rds of our rainfall you have to look at almost 30 days.
Weather Underground is a great source for historical data.
Based on your observations of little or no runoff during or following one of the downpours, it would seem that your property is already well suited to take advantage of the quick bursts of rain you receive. That being said, small earthwork features on flat land are able to hold back a tremendous amount of water relative those features on hilly ground, so you might be able to get a modest improvement for a modest expenditure of work.