Musar zu Jeschijahu 61:8

Not only that but even if one does a Mitzva (good deed) during the time of his work, it will not be considered a merit but rather a sin in his hand. For a sin cannot be considered a Mitzva. And scripture states: "[I am G-d who loves justice and] hates theft in an offering" (Isaiah 61:8). In relation to this, our Sages of blessed memory said: "one who steals a measure of wheat, mills it, bakes and recites a blessing over it, is not blessing but rather blaspheming as written 'and the robber who blesses blasphemes G-d' (Tehilim 10:3)".

Therefore, he necessarily must attain comprehensive knowledge of the Halachot to their full depth in order to know the extent of reach of the branches of the mitzvot.

For man is not born wise and cannot know everything. But by studying the matters, he will be awakened to what he did not know, and he will contemplate on what he did not grasp previously, even matters not found in the books themselves. For when his mind is awakened to the matter, it goes and observes it from all perspectives, and draws forth new understandings from the wellspring of truth.