The game is actually supposed to be a repeatable experience involving a hefty amount of grinding, and is geared towards ultimately turning the Warden into a sex-machine, virgin or not, submissive rather than dominant. Yes, the Amazon run may be a faster run, but that also means missing at least half of the game's content, compared to sub-slut run. There are no 'sadistic' victory scenes for Karryn, only defeat ones, which are putting her in progressively submissive positions (blowbang, human urinal, restrained gangbang in solitary cell, pillory gangbang with spanking...). There is scarcity of undeniably sadistic sex moves compared to the arsenal that a maso slut Karryn can have and use to win 'battles' just by sexually pleasing the prisoners. Titjobs and handjobs are just unconvincing as sadistic acts. 90% of the available passives are sex-machine building blocks. Possibly 50% of available edicts are Prison-to-whorehouse re-decorating blocks.
Even when equipped with the Pearl Ring (the accessory Yukariin mentioned), Karryn needs to keep on suppressing her pussy desire if she wants to remain a virgin, so this can be a fun and frustrating challenge even for ultra-slut runs.
So yes, there are two routes possible in this game: an honest slut and a slut-in-denial.