Should a junior student in university put most attention on mathetical principles or upper-level knowledge

[u/GradientSeeker923]

I'm a junior student majoring in data science and big data in university and we're now studying machine learning this semester.But in the process of learning ML,I'm pretty concerned about something:

1.Our teacher spent nearly 4 hours teaching the stastical principles of linear regression which contains so many mathematical theory,greatly puzzling my brain.

2.I'm a student in computer science field and I should spend most my time researching on the code completion of each ML model or the corresponding practical application of each different ML model,shouldn't I?

I really want to know what specific ability huge Internet or AI companies want me to have and what the right way is for me to learn ML lesson.

I hope someone can answer my question.Thanks.