Welcome, Becky!
It depends on what you are growing, and the reason you are mulching.
If protecting tender perennials or die-back shrubs from extreme cold, use a thick layer of coarse, open mulch around the root crown every fall, because it's still impossible to reliably predict what kind of winter it will be. Most will need the mulch removed gently in the spring.
When growing woodland plants in more sun than they might like (whilst the trees grow) use an inch or two of medium-texture mulch to keep their roots cool. Eventually, the tree leaves will take over that job--and then some!
In perennial and shrub beds, an inch or less of fine-textured, rich mulch--such as compost or composted manure--applied each spring will help keep the soil healthy.
Yep, it does look like every year.

if youve got it yes. It will help replenish nutrients cut down weeds and help retain moisture. Or more specifically as tugbrethil says.
welcome from me too.