Redemption period in Texas is 180 days to 2 years depending on the type of property after the dead is filed. Even with the shorter periods seems like title insurance companies don't want to issue insurance before a potential 2 year redemption period is up.
In my experience...there are very few over the counter sales of interest. I won't say never, but seems like rarely.
Now with OTC sales you could get lucky if you are buying properties that have been transferred to the taxing entity from years before, you might be able to get around the 180day-2year rule. Have not tried that or had any experience with that yet.
Some places don't do OTC sales by the way, they just put them in the next auction.