if you are in an area with a lot of callers and everyone starts using the same sounds / sequences those dogs will get educated quick.
switch it up.
last night we didnt get a reply for almost 30 minutes or longer. we got a reply and about 15 minutes later we spotted them. two came in thru the high grass, we only saw them when they were "jumping" coming to us. we set up for them to come across the cut field but NOOOO, they had their own idea 
one disappeared on us and one got close enough for me to whack, one is better than none. sometimes it just takes awhile
