Need some help and encouragement. I’ve been doing FA and UW systemwise

Hi guys. Need some help and encouragement. I’ve been doing FA and UW systemwise, but as i progress to the next system it seems like i’ve already forgotten all the concepts and material that i studied last week. And the things that i covered a month ago, seem like things of distant past now idk why. Is this normal to feel this way? How do i deal with this? Should i revise what i studied regularly or first complete everything and then revise FA and uw notes cover to cover?? Any help will be appreciated. Thank you_10_