Unless you are freeriding or extreme downhill, the stories of discs trashing a wheel are highly overrated. I have raced and jumped with 24 spoke wheels without any probs of untensioning. The important thing is to make sure your tensions are high.
While it is on the stand without the tire on the wheel, tap the spokes while you are truing. It should have a clean resonance for several seconds. Do not worry about 100 percent match in tone, but make it true and tight. Then grab the spokes where they make the final cross and see how much it takes to move them in relation to eachother. It should take a moderate ammount of force if they are set right. What loosens a wheel is when one or more set of spokes is loose and allows the wheel to distort.