Do the lessons contain audio?
NativShark has both male and female audio for all example sentences and vocabulary flashcards.
Voice actors for NativShark are asked to speak as if they were saying it normally, not recording for a learner.
This helps your ears get used to how people use Japanese in real daily life situations, and not the unnatural and unhelpful stuff you’re likely to find in textbooks and many other learning resources.
Information about unnatural audio can be found here in the “The second major problem” section
Information on fast audio can be found here.