So How Does That Happen?

Story. (And more detailed account here.)

With sexual abuse cases, each "act" is a separate offense. You can technically have multiple crimes occurring between one defendant and one victim within a matter of minutes. (In this case, it looks like three victims on multiple occasions, but you get the idea.)

The judge even stacked the sentences. (Texas is a bit weird: If all the cases are heard by one jury, the jury only assesses a punishment for each crime. But it is the judge, not the jury, who decides whether the sentences will be served consecutively or concurrently. ) But based upon the law in place at the time* of the offenses, he wouldn't have been eligible for parole until the passage of 30 years even if the sentences hadn't been stacked.

But this closing argument of the defense didn't work too well: “I respectfully submit to you that is BS. If it was as 'traumatic' as they indicate, they would be able to give you [specific dates and times of the acts]. Simply because it’s shocking doesn’t make it true.”
* Texas even made the punishment stricter for offenses occurring after 9/1/07.

Edit: It looks like the headlines in all the papers will be "Man Receives  4,060 Years In Prison." I don't understand that. He received 40 "Life Sentences" and, actually, an additional three 20 year sentences. No where in the books does it say that "Life" equals 100 years but that's what everyone is running with.