What is a realistic return on value investing?

[CityFarmer]

I think there is a different if you considered the performance of the idle cash as well. If every month you set aside say $300 from your pay to invest then your return is 21% based on XIRR but say if you allocated $3600 at the start and transfer $300 very month into a Plan (say call it Plan A) then together with the idle cash (say Plan B) the XIRR will be just 11%.
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So the performance of you Plan A is 21% and Plan B is 0% giving an overall 11%.

Yes, in other words, the opportunity cost of the idle cash is 10% over the period.