The problem of congestion control in wireless sensor networks is very important, especially in very dense networks. In this work, we use a simple packet repetition scheme as congestion and event-reliability control. In contrast to other works on the performance study of such a scheme, we use a random radio pathloss model. We are motivated by this choice, because the radio model usually used in most of studies on wireless sensor networks is deterministic. However, this is not the case encountered in real hardware. Here, we show that the analysis of such a scheme by simulation is not trivial when more realistic radio models are used. We emphasise this problem by comparing the differences of simulation results with respect to the non random pathloss case, also known as isotropic model. As expected, simulations confirm that radio irregularities can not be neglected and the efficiency of event-reliability based congestion control should be properly revised. This aspect calls for new mechanisms of coordination among sensor nodes.