I'm not entirely sure what you mean by a "superstitious practice," but if you're asking whether sacrifice was used as a form of execution, then the answer is a definite "no."

One of the most famous sources of Aztec law are those laid out by Motecuhzoma Ilhuicamina (the great-grandfather of the Motecuhzoma who greeted the Spanish). Durán's History of the Indies codifies sixteen laws from him, ranging from sumptuary restrictions on dress to the estblishment of a system of courts and judges to punishments for adultery. Capital punishments are indicated for some of these offenses, including adultery where the offenders were "to be stoned and thrown into the rivers or to the buzzards" (p.210). Indeed, adultery, along with murder, and public drunkenness are some of the most consistent capital offenses mentioned. Other crimes, such as theft, could merit execution if the amount was substantial enough, but more often material restitution was called for, up to having the offender sentenced to be enslaved by the one they wronged.

For the capital offenses though, stoning, clubbing, or strangulation all appear to be standard methods of execution, most often carried out publicly. The actual executions were carried out by the achcacauhti (typically translated as "constables"), of which there were several different titles, though whether or not this reflects differing duties and responsibilities are unclear. The two most consistently appearing are the Quauhnochtli and the Atenpanecatl, both of whom were commoners. Sahagún writes in Book 8 of his General History of the Things of New Spain that to carry out executions they would "strangle one with a cord, or stone him to death, or slay him under wooden staves, beaten" (p.41), though he also writes that an offender sentenced to death might also be cut to pieces by the achcacauhti (p. 55).

Whether a noble to be judged in the high court at Tlacxitlan, or a commoner at the Teccalli, the offender would be kept in a wooden cage during the trial and deliberations, as this page from the Florentine Codex shows. This not a punishment in and of itself, merely a temporary measure, and Sahagún even mentions that judges who were found to be drawing out or needlessly delaying rendering a sentence could find themselves seized and executed.

Now, contrast all this with how sacrifices were carried out. Those who were sacrificed generally fell into two categories: war captives and ritual individuals, with the former making up the bulk of sacrifices. The latter group was composed of individuals selected for specific sacrifices, such as the women who played the role of goddesses or the children sacrificed to Tlaloc at the start of the year. I've written about this topic previously, if you are interested. The two categories could overlap, such as in the case of the war captive chosen to live as the embodiment of Tezcatlipoca for a year prior to his sacrifice during Toxcatl, which I've also written about.

In the case of the ixiptla of Tezcatlipoca, he would live as near royalty for his year in the role. Likewise, the women who filled the role of goddesses would be elevated and feted for period of time before their sacrifice. All of this is a far cry from a wooden cage.

Even for more "standard" captives, mistreatment by their captor was taboo. True, the captive would essentially live as the slave of his captor, being kept in his home, but Sahagún notes care was taken to ensure the captive did not grow sick (p. 83). Further detail of the intimate relationship is shown in Book 2, which contains the famous passage of warriors refusing the ritual cannibalism of their sacrifice:

But the captor could not eat the flesh of his captive. He said, "Shall I perchance eat my very self?" For when he took the captive, he had said: "He is as my beloved son." And the captive had said: "He is as my beloved father" (p. 54)

The act of sacrifice was not a punishment, it was a sacred and solemn act, and one that young men were constantly reminded might happen to them. Their deaths were not seen as gratuitous but a sad necessity, with even the priest who shepherded captives to their final end during the rites of Tlacaxipehualiztli mourned them, and upon their deaths "he went weeping, he went howling like one bereaved; he wept for those who had suffered, who had died" (pp. 54-55). The sacrifice gave his life not in a sadistic rite of torture, but in fulfillment of the cosmic debt humanity owed to the gods who had sacrificed themselves to grant life to the world. But with life comes death, and the act of sacrificing a captive also served a reminder to all involved of their own mortality. The sacrifices, particularly if they conducted themselves bravely, were esteemed and their souls thought to the highest heaven, right alongside warriors who had died in battle.

Sacrifice was not a punishment. If anything, it was seen as an honorable way for honorable men (and women) to die. Those who went to their deaths were expected to hold themselves up as righteous and brave representatives of their people, and those selected to live as the avatars of gods were picked for their exceptional qualities. Capital punishment, on the other hand, was reserved for those who exemplified the traits despised by the Aztecs: greed, cowardice, dishonor, lack of self-control in drink or sex. A captive ascended to heaven as one of the Quauhteca (eagle-men) to soar across the sky with the Sun. A prisoner got a club to the back of the head.

There's always room for discussion, but perhaps the section Human Sacrifice and Blood Sacrifice from our FAQ will answer your inquiry.