I repeatedly use it, and as you said it is brief so going over things twice is always nice. I find it is better for key terms rather than getting good at exams or timings. More advanced longer revision tasks are better tackled with a revision guide, most noticeably English, History, Geography and Religion. However learning definitions, this is really great. Seneca is useful but buying a few books would be beneficial, they're also really useful. But for anyone else going through GCSEs in particular, just do a little bit of everything, Online stuff, Mind maps, Highlight stuff, Write some paragraphs some days and bullet points on others. It'll keep you from getting bored too. Good luck!