Speaking as someone that hates wasting any stamina at all, the joy of beating chapters five and six through trial and error actually made the lost stamina worth it for me, which I'm not sure I've ever experienced in this or comparable games. Both can be VERY frustrating (the light areas in particular are fiendishly difficult, seemingly bent on messing you up), but boy does it feel good each time you beat a new level.
And to confirm, yes, 50% reduction and HM are generally the key.
Edit: There might be a few other tricks required for one or two of those levels though