Under what circumstances is it important to adjust the capital asset pricing model for firm size? Why?

Question:

Under what circumstances is it important to adjust the for firm size? Why?

Capital Asset Pricing Model
The Capital Asset Pricing Model (CAPM) describes the relationship between systematic risk and expected return for assets, particularly stocks. The CAPM is a model for pricing an individual security or portfolio. For individual securities, we make use of the security market line (SML) and its...