Depends on all kinds of factors. This time of the year they reds are matting and paired up! If they are hungry you will call in two with 5 min of bulb squeaking or less.
Fox vocals I let them rip for long periods there after and the reds will run right to the speaker! They come from afar hence why it takes longer! If you can get your hands on a cheap fox mount thats even better yet. You might pull in a coyote with the red decoy too.
I have called in large reds using GFP sounds! In the fall they don't hang around long. Actually let the JS Red and Gray combo or Red and Gray Fight rip. You will call in love sick reds!!!!!