Ideally it would be good to continue reading previous notes, however it will start to pile up as you progress in the year and it'll be too much to read. So reading notes relevant to the current topics, especially the tested topics in assignments and exams, would be more helpful.
The basics of a subject become easier to remember when it connects to further topics; so if you really need to cram in content, it's not necessary to relearn what you confidently know.
For note-taking, make it concise and clear. Write statements rather than paragraphs. Highlight key metalanguage and write simple definitions. Make word connections to visually memorise words. It'll make it easier to skim through notes and strengthen memory recall, making it quicker to revise through notes.