Why is their such a broad time frame of 5-to-life when it comes to sex crimes? This range is put in place to make sure that the punishment fits the crime.
When a case goes to trial both the defense and the prosecution are obligated to bring with them all the details, evidence and witnesses they can help win their case. Based on their presentations, questioning and the jury pool, you would be either convicted of, or acquitted, of a crime. The term 5-to-life refers to the amount of time you can receive both minimum and maximum for a crime with all the above considered.
You can also learn more about the penalty for sexual assault in Texas here.