The distribution of IP addresses depends to a large extent on 4G provider. Some of them reuse IPs and you can get the same IP after you change network mode 4G > 3G > 4G. The same applies to IP addresses allocation space. You can request IP change as often as you want. Resetting network mode takes 5-10 seconds. There is not rate limiting. From time to time reconnection fails but it has nothing to do with rate limiting. Sticky IP is an issue for some 4G providers but, again, it has nothing to do with rate limiting