I did 5. It's manageable but not really worth it in my opinion, although I did take science subjects, with maths and German, so maybe the workload will be different (I only ever had to write the odd essay for General studies, and towards the end of the year something like 2 German essays a week. The rest of it was stuff like maths problems and worksheets, where the time it takes to complete depends on your ability more than anything).
My advice is to pick courses that are both academic and complimentary. There's no point trying to achieve balance at all (If you're that unsure what exactly you want to to, stick to core respected academic subjects, like both English courses, History etc.). That way your options are open and you've got a strong foundation in the essential skills needed for most arts degrees.