I have duck hunted for the past 47yrs. In my experience unless you know what your doing with a duck call leave it in the store or keep it in your pocket. I admitt I am not the best fella with a duck call never had to be. Scout and find where the mallards want to be. Get there early and be well hidden, you won't need a duck call. Mallards are wary birds, especially the educated ones which means the ones that have been shot at. If something doesn't sound right, look right, or moves that shouldn't they will flare off. If they pass over the decoys once and don't land and are setting up for a second pass with no signs of cupped wings. Best be giving it it too them if there within range because not likely they will be back. Something was not right.
I learned two calls for mallards, "the highball", a hailing call for birds that are far off. And the "feeding call". Over all I use a duck call very little as I learned long ago finding a good location where the ducks want to come to and staying well hidden so nothing is out of the ordinary when they arrive is far more effective for putting ducks in the bag than a duck call.
Years ago when one fall I was playing with duck calls and tapes. I was out scouting one day and came across a fresh cut corn field with hundreds of ducks on the ground and maybe a hundred more circling in the air. I stopped the truck and opened the window and listened and watched until they where mostly all down. I then played what I thought was my best tune on the duck call. To my shock the whole field of ducks lifted off and left for parts unknown. My duck language was obviously insulting and most likely contained the alarm call which is three consecutive loud distinct "quacks". After that little experience I perfected my Highball and Feeding chuckle, but for the most part kept the call in my pocket.
I still have the original two calls I bought in the the very early seventies, one is an "Olt" made from black plastic. The other is a wooden call single reed that has an adjustable pitch, don't know the brand. Neither has been outside in years. My opinion and experience with geese is no different than ducks.