Lot to parse here, so forgive me if I miss or gloss over something. In general, you should have quite a few opportunities to use Hard Times if you're saving it for ambushes and the big fights at the end. And those are exactly where it's needed, and should be used.
I should say that in the normal, middle-of-the-road fighting style for this chapter, you should expect some battlesex to happen. The goal isn't to avoid it, so much as to prevent it from backing you into a corner and forcing a loss. If you want to try to style and avoid it you can of course, but the balance, especially in the later game, isn't designed with that in mind, so it's going to be challenging. I can re-play the last three fights with hypno stuff on again eventually just to test, but from memory it shouldn't take more than one or two reloads to get past them if you're saving after each, and that's just if you're unlucky.
And that soft lock on the final 3 fights when lacking the special Dazzle for Hard Times is intentional. Right now it's just a bit frustrating, but eventually it will end up forcing players who screwed up their item management to go the host club route instead.