Effectiveness
While some proponents of time-outs insist on silence and stillness from the child during the time-out, it is easier to use a "release-contingency," such that the requirement is only that the child is sitting peacefully at the end of the time-out period. Those who use time-out for children to get anger and frustration "out of their system" or for children to think about their behavior, are using time-out in a way that is different than those basing it on operant behavioral principles (that time-out from positive reinforcement may reduce recurrences of the unwanted target behavior).
Spanking sometimes is used as a penalty if the child refuses to serve the time-out. However, spanking children is illegal in several countries, and other back-up penalties could be used, such as privilege withdrawal substantial enough to encourage serving time-outs instead.
Read more about this topic: Time-out (parenting)