We might be hunting the swamp, where we don't see them coming over the tree's, from behind or something. I'll give a soft hen quack, as they pass us, then watch them fly down the swamp checking other holes before circling back to me. I never hunt public land. I'm very confident that this technique works in our situation and because of experience doing this, can pretty much determine, for myself, if I need to be calling or not. Other times a group of Widgeon might come sailing in, trying to decide between our flooded hole or the sheet water 200 yds behind us. A little whistle Widgeon Call gets them to come back around again. Flock of Mallards, circling our many decoys in our 100 acre flooded corn. There are usually a lot of ducks there - they are not quiet - they make a lot of noise. Again a soft hen call or a drake humm, adds just a little reality. We're very aware of when to shut up. In the swamp, I use that little Gadwall beep which is very effective, cause that's what ducks here when flying up and down the swamp. We rarely have 360 viewing from our blinds or the cypress tree, we backed up too - get caught all the time. It's like trying to get our guns up when that Woodie comes ripping past us in the morning - "why didn't you shoot that?" "I was letting you have it". As far as not calling - I spend a lot of time observing ducks when they're not being hunted. Have a pond behind our house - at one time had a broken wing mallard hen on it. I'd go down and flush the ducks that had joined her. Every time she gave that hen call, she could turn those drakes back. They'd fly by and try to leave pattern, she'd give the call, boom turn em right back like they were on a leash.
What kind of holes do you hunt, where you always have time to call them in or if they're close they've already committed?