Run it once a week...
This pretty much, Ccleaner is handy for clearing out cookies, temp files, internet cache and assorted other "stuff" from time to time. Wheter that produces any improvements or benefit at all these days is another matter entirely. I suspect there's a large placebo effect in force rather than tangible gains with this stuff now.I still run CCleaner every now and then, but I really don't think it's needed these days.
Nope you absolutly do not need to run a registry cleaner.