What amount of time is abandonment in tx?

I believe it is at least one year, with the intent to abandon.

ABANDONMENT. The court may grant a divorce in favor of one spouse if the other spouse: (1) left the complaining spouse with the intention of abandonment; and (2) remained away for at least one year.

Is there a special reason you want the abandonment ground to be used at all?

Texas has no fault divorve & the amt of time from the time of the divorce is filed to when the final decree can be issed is very short. So unless there is a lot of disputes especially with kids and/or a lot of property involved, the only ground you need legally is "I want out". Proving one of the other grounds may affect the property division however, an atty would be able to answer your questions best & many do give free consultations.

This site has a lot of divorce info specific to each state, here's the TX link:

DivorceNet - Texas Divorce

yes, with the exception of just leaving the child at walmart and driving away, which is from the first minute you do it, the other has little value in TX unless you want to use it to get more money during divorce, or give them less visiation during custody agreements.