How effective is to apply SWOT Matrix in a real business scenario?

It depend on the size of the business and the purpose for the analysis. If it to create a portfolio and information in a nutshell then yes SWOT will be enough to just give the basic idea of the firm's strength weakness and the threats and opportunities present. If its to carry out detailed analysis for information about which market to penetrate then you would need to use more methods like an Ansoff Matrix, SPSS, and large amounts of Qualitative and Quantitative methods to understand the the actual weaknesses and threats from the dynamic market first hand rather than use second hand sources of information.