Each club is required to submit 29 of their official 30-man playing squad to the NRL by March 1\. The final spot in theses rosters can remain free up until June 30.
With Suli departing the squad is at 28, which leaves only a few days to add the 29th player.
I believe the Top 30 would normally be seen as sufficient now to cover injuries? I'm not sure about the rules for calling up the 4 development players.
I went looking for players used data; couldn't find 2017 but in 2016 only 5 teams used more than 30 players (Warriors 34, Souths 31, Manly 31, Roosters 31, Knights 35). And if you note 3 of those teams only used 1 extra, which should be reasonable enough to apply to NRL for. Obviously this doesn't account for multiple injuries in the same position.
Tigers used 30.
Also of note is every club that used 30 or more players finished outside the Top 8\. In fact only Saints (29) and Parra (28) used less than 30 players and failed to make the Top 8\. The av # players used by clubs in the Top 8 was 26.5.
I really think we should try outside the square and use every player + extras we have at our disposal on a rotation basis..