Signal re-amplification, re-shaping, and re-timing (3R) opto-electronic regeneration is a crucial function to scale elastic optical networks. These devices are especially important on large-scale optical networks, enabling long-distance communications. In this work, we analyze the impact of these devices on the quality of service in wide-area optical networks in terms of blocking probability. To this end, we performed network simulations to obtain the blocking probability of users on diverse scenarios, modifying the number of regeneration devices per node jointly with several parameters such as link distances, bit-error-rate (BER) threshold, and network capacity. We use a physical layer model considering linear and non-linear impairments to compute the maximum reach of each communication for a given bitrate and modulation format for a variety of BER thresholds. The results show the importance of using 3R regeneration in wide-area elastic optical networks (EON). Notwithstanding, a limit was found where adding regenerators per node does not substantially improve the blocking probability. Therefore, a cost-benefit analysis must be done considering the cost involved in installing more of these devices.