Aki 2018 was the last time of 3 Yokozuna fighting for the whole 15 days. We are down to 2 Yokozuna since then and it doesn't seem we will see both going the full lenght very often.
If one of the 3 Ozeki finally has his breakthrough moment with back-to-back yusho, that very basho could be 01/20...but we're talking about the kings of kadoban here, so don't get too excited. If you think we'll have to wait at least until 2022, please specify the basho in the comments. Guessing the correct rikishi will earn you a forumboshi (bragging rights).