I have all three cans. li'l can....Doe bleat original....estrus Big Can.....suppose to travel farther on windy days, never used it yet.

I really don't think there is a rhyme or reason to them. I usually flip mine a couple times every half hour. I have shot deer using these cans. I have blind called them in early season with the li'l can and have also seen deer changed there path to come my way. I kind of read the deer. If I see one and he isn't coming my way I will flip the can and see how he reacts.The deer will lift its head usually if it hears it, then maybe again if it's not looknig my direction so it knows which way it came from. He may turn and I have also seen them ignore them completely, If they do ignore it I will not just keep flipping the can. I use the li'l can which is more of a contact bleat, which kind of means hey I'm over here. Thats more for early season. I wouldn't want to use an estrus bleat way ahead time. Last year I brought in a big bodied small eight during the rut with just the li'l can. When the ruts on you can mix buck grunts with a couple flips of the can. Rattle/can. I think the main thing is just not to OVER CALL. Sometimes I will go out and not call at all, unless I see a deer thats moving in another direction. Sometimes you can flip the can in your pocket just seems to quite down some if need be.

I am not an expert. Just some of the things I have tried and seem to do ok with. Maybe someone else can give you better details!
Good luck!