One parent will seem oblivious to a behavior that drives another parent up the wall. If it is a behavior that children simply outgrow, the behavior will be a problem for the parent on the wall. Parents can always ignore the behavior and try to maintain some perspective. When a behavior is considered normal, parents should not take the behavior too seriously. If we expect problem behaviors to be temporary, they usually are.
Time away leads to a better perspective.
The best way to maintain perspective during any difficult phase is to get away from the child. Whether the child is 2 or 15, separation time is often a good solution. Children can't be pleasant all the time and neither can parents. Going out in the evening is wonderful if the parents can arrange to return when the kids are in bed and asleep. Regardless of what a child has done during the day, just one look at a sleeping child can put everything back into a better perspective.