It's important to continue to make calls to prospects when they have an answer, just in case life has happened. It tends to, and plans slip the mind and catch them at a bad time. It's always not only possible, but likely that they just haven't had the right amount of time to sit down and talk and mean to call you later and never do. So trying to find them at the right time really makes quite a difference. I have had a minimum and maximum call ratio in the past, where I have to make X amount of calls and stop at X amount of calls, but I find three calls to be the most adequate without annoying the person to never want to talk to us again, or actually being able to reach them because maybe third time's a charm.