This is a really good topic for discussion. The opinions stated so far are very valid and applicable to the situations and conditions that each of the individuals hunt under. Small properties, traditional roost sites, and intimate knowledge of the properties by the hunters all point to a lack of need for roosting gobblers. On the other hand, there are definitely situations and conditions in many places where using roosting tactics to find birds is a very important component in the success or failure of a hunt.
I'll use my own situation here in NM as a prime example. Here, we have hundreds of thousands of acres of public land (National Forest) to hunt. The turkeys are not evenly distributed in that acreage. There are large areas that have lots of turkeys,....and there are large areas that have few, if any, turkeys. Our birds are also very vocal on the roost, both in the evening and morning, and as such are very easy to locate. Because this is mostly public land, there is no exclusivity in hunting them.
Our hunt strategy is to go out and cover as much country as we can in the evenings at dusk when the birds gobble on the roost. It is a given that a lot of gobblers will be heard. The trick is to determine which birds are in locations that gives the hunter the least likelyhood of other hunter interference, as well as makes them most susceptible in terms of the hunter being able to get a good set-up on them. Your success or failure depends a great deal on making the right choice in which gobbler(s) you decide to hunt on any given morning.
Someone who has never hunted here, and who is not familiar with the country and the value of roosting our birds, is at a great disadvantage. Make a wrong guess on what area to hunt and you may find yourself in a canyon or on a ridge where you are met with dead silence at daylight on a morning, while a couple of miles away, there is so much gobbling going on that it sounds like a turkey farm. Finding birds to hunt here is as simple as using some basic roosting tactics and locator calls, and covering a little ground.
Here, knowing how effective roosting can be and using it as a primary hunting tool can make all the difference in the world.