The order of reactions is decided using random numbers in normal execution of CCM-based systems. Random number generator is built-in in CCM-based computational language SOOC. However, random number is not strictly necessary in CCM-based systems. Deterministic ordering of reactions sometimes works well. What is important is probably that the relation between the logic of the CCM-based system and the logic of reaction ordering. The CCM-based system works normally if they are independent, i.e., there is no relation between them.
In the N queens problem, deterministic ordering sometimes causes a limit cycle (dynamic looping). However, if N is not six, a solution is found in probability more than 0.95 experimentally, and the computation is faster because of no random number generation overhead.
The normal relation, or the independence, between the system logic and the ordering logic is probably not always required. For example, in a sorting system, if the logics are independent, the order of execution time is O(N^2). However, it may probably be O(N logN) if there are appropreate relationship between the logics.