Not only does mulching reduce the need for watering but it also cuts down weed growth. I have even thought about using some on my container plants but the bales of mulch are too big for me to use. Have used quartz gravel as an ornamental mulch for some of my potted plants but it, unfortunately, becomes a nuisance when you need to repot the plant.
Now, in our area, all tree trimmings & cuttings are put through chippers for eventual recycling as mulch or compost. The large ghost gum, over the back of our place, sheds its bark each year, & the owner of the tree has the long strips of shed bark chipped. Very handy. They have their very own mulch growing in their backyard. It also gets rid of the huge amount of shed bark strips from their yard.
Mulch should be applied quite thickly, about 15cms or 6ins deep & is recommended for all types of gardening. Even trees & shrubs will benefit from being mulched.
Here are links to some articles on mulching.
How To Mulch
Mulching Techniques & For Trees