Most of the cities in the Houston suburbs test weekly with a couple of outliers:
Baytown- Wednesdays at 9 am
Texas City, & Bayou Vista- Wednesdays at 12 noon
University of Houston- 1st Wednesdays at 1 pm
Mont Belvieu- 1st Wednesdays at 4 pm with quiet tests every other Wed.
Pasadena- 1st Thursdays at 6 pm (Will start testing on Saturdays at 12 noon in May of 2019)
Friendswood- 1st Fridays at 12 noon
La Porte & Deer Park- Saturdays at 12 noon
Rice University has a small system of ATI HPSS-16 sirens but testing times are unknown
Galena Park has three Federal Signal 2001-SRN's but I am unsure on when they are tested.
Katy had a system of four Sentry 40V2T's before the city took them offline