Single stock investing: does it work?

This is a high risk high reward strategy. Some of the pre-conditions one where identify

1. A prove business model is mandatory. Cant do this on unproven business models, nano and microcaps. Preferably a midcap so that there is enough growth
2. The sector/industry/company must be going through a temporary and fixable problem.

• Divis correction in 2017 -company specific- I took advantage of it
• Cement stocks going through margin contraction due to raw material costs right now

3. Valuations must be very cheap it is a corollary of point 2
4. Some biggies started accumulating
5. Good strategy to trail once in a profitable position
6. Good un-emotional exit strategy
7. Being invested or invest at the beginning of a bull market to make sure that the stock’s trend is confirmed as well as market conditions are conducive

Open to more suggestions