If I were you, I'd save 300 and use them during event to get Han and go 1/2way to get roshi. By the time you save another 300, GNW treasure might already be release, and you could finish roshi and start pulling from there. For now your only concern on your own server should be 9tails and gnw- during first you arent using any treasure ninjas anyway, for the latter- depends on your group. If you having no rares yet doesnt influence gnw result, I say save scrolls. You will benefit from this in a long run. Also at this point, skipping kage treasure completely might be a good idea, even though few kages get a skillbooks in the far future, ones worth noting are danzo, susanoo sasuke and Ay, but you wont use those ninjas as water anyway.

If you look up the meta in china, we slowly will be getting 2nd stage akatsuki members, anbu/uchiha teams and others. Getting a headstart with seal scrolls for gnw treasure will also set you up for a long time, when it's finally released.

For me, the difference between top1 and top3 in ranked is nothing. About duels- personally I dont care about them either. If you can still plunder, then theres nothing wrong if your groupmate can beat you in duel, what's important is that you should b able to win fights that matter. Also when pulling for basically anything, ask yourself, if you get any rare before your final target, will it improve your team right away? If yes, then that's the only excuse to pull before perfect rebate. Because if not, you used 60/120/any number seals and got nothing- even worse, you lost potentialbetter reward. Doesnt bring you anywhere closer to your final goal than just waiting with seals in inventory.

Yes, my reasoning was purely about getting max ammount of seal scrolls over time. Before merge hits your server it's gonna be about 6 months since server release, that's why time period where you can farm server related dailies (9tails, gnw, plunder, rescue jinchuuriki) without ANY competition is the time where you should maximize strenghtening your char and get as many different items as possible. May sound silly but that's why i put such emphasis on getting the absolute MAX out of any rebate. Your seal income is steady now, but if you dont play it smart, you will fall behind people, who did that correctly. And you will notice the difference once that happens. How does getting free roshi sound? Or simply 200 more free seals th*most everybody else? Because thats the X month effect of doing rebates correctly.