Mouse wrist rests are a good idea in many cases, but the same warnings apply. In actuality, some are good and some are probably bad. Some are right for some people and not for others. The only kind of ergonomic keyboard that many ergonomists can recommend in good conscience is one that can be configured to look exactly like a normal keyboard. These boards are hinged and can be changed to a new shape gradually.
Conventional practice recommends rest breaks about fifteen minutes long, every two hours or so.
This is insufficient for single-task work such as typing. These should happen in addition to the normal fifteen-minute coffee breaks. In reality, posture change seems to be as important as posture correctness, especially with regard to the intervertebral discs in the spine. These discs lose fluid over the course of the day because of the weight they carry. It appears that posture change is essential to help pump fluid back into the discs.