Allocation to a stock depends upon valuation comfort & quality of Business: http://manufacturedluck.blogspot.com/2014/04/fools-wisdom-4-alternate-approach-to.html
https://forum.valuepickr.com/t/towards-a-capital-allocation-framework/504
https://forum.valuepickr.com/t/the-art-of-valuation/505
Concentration Vs Diversification depends upon Trade Vs Investor Mindset, Time Horizon & quality of stock in your portfolio: https://marketsense.substack.com/p/portfolio-construction