IoT-technology is gaining a wide popularity over a large range of applications including not only monitoring of structures but also management and control of smart-systems. An IoT-system, in general, is composed of a number of IoT-devices which form a wireless decentralized setting as they get installed over a specific area to serve a particular purpose. The structure of the underlying wireless network depends on the structure of the target where the system gets deployed and hence, widely varies based on the exact application. Such structural variations often have an impact on the performance of the underlying IoT-protocols. Unfortunately most of the network protocols do not take care of such issues explicitly. For instance, although there have been quite significant development in the data-sharing protocols, especially with the advent of Synchronous-Transmission (ST), most of them are designed without considering the variation in the structural formation of the base networks. These protocols are tested over either in small scale simulated networks or in testbed settings bearing fixed/homogeneous structures. In this work, we demonstrate that the property of self-adaptability in an IoT-system can enable it not only to run faster but also save substantial energy which is an extremely important issue in the context of low-power system, in general. In particular, we design and implement a flexible and structure-adaptive many-to-many data-sharing protocol FlexiCast. Through extensive experiments under emulation-settings and IoT-testbeds we demonstrate that FlexiCast performs upto 49% faster and consumes upto 53% lesser energy compared to the case when it does not adapt to the network structure.