It depends on you. If you wish to measure your overall performance accross all asset classes, add real estates as well (inluding stamp duty/registration + maintainance / rent etc. costs). Or you can measure individual performance for stocks.
XIRR is very simple to use and if you have all transaction in separate sheets, it takes 5 mins to generate it. The period should not matter much. I personally measure my XIRR twice a year to get a general idea. But do not focus on the CAGR number too much. If you do good investments, CAGR will be taken care of. In the end the net worth matters more than any other number

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