Time Slotted Channel Hopping (TSCH, termed also Time Synchronized Channel Hopping) is one of the medium access control modes that is defined in IEEE 802.15.4e standard. TSCH plays a vital role in the development of the Internet of Things (IoT) applications such as smart city, smart home, and smart factory. For reliable communications, it leverages time slotted channel together with time slotted access capabilities. Moreover, it serves deterministic low-power mesh network deployed for critical applications with high reliability and low latency. However, it suffers from problems that may seriously deteriorate the system performance. As an attempt to identify the scheduling technique problems, in this paper, we first presents an overview on existing scheduling techniques, rules, and their challenges in TSCH-enabled IoT applications, and second, we study some recent emerging scheduling-based proposals that benefit from intelligent and machine learning techniques to avoid such scheduling problems. Therefore, increase the efficiency of the IoT applications. This survey inspires researchers to create a reliable TECH communications for critical IoT applications.