Since SA started months ago, I already noticed that past the 6 weekly SA, although it consumes no Stamina, it still requires the adequate amount of Stamina needed to start that SA (i.e. 30 for Difficult, 20 for Normal, 10 for Easy). So hopefully the dev can just change this aspect of it.
Another thing I noticed about SA is that after the 6 SA of the week is done, the 7th SA onwards will not give you a score to add to trying to compete in the SA rankings. Your SA ranking chance is limited to that 6 weekly SA.