Depends on the vehicle, load, and conditions.

In general, it's unnecessary in a passenger car on flat land in normal driving conditions and will hurt your fuel mileage.

Anything you do that hurts your fuel mileage also implies the vehicle is operating below peak efficiency, therefore it must work harder to go the same distance, which means more wear and tear.

There are circumstances in which it makes sense, but they are unusual. Fore example, there is a hill near me where I accelerate away from a junction. I reach the point at which I should change from 3rd to 4th just as I reach the speed limit and the hill flattens out, so I go straight to 5th. Coming down the same hill, I often go from 4th to 2nd if the junction is clear to accelerate away quickly. So in these circumstances - where a gear change coincides with a change in conditions - it may be reasonable. On the other hand, it is never wrong to go up and down the gears in order.