Terms to search for include "blocked practice" and "interleaving"; the latter is also known as "mixed practice" or "varied practice".
For instance, see https://effectiviology.com/interleaving/ (excerpt below)
Interleaving is a learning technique that involves mixing together different topics or forms of practice, in order to facilitate learning.
Interleaving helps people retain new information, acquire new skills, and improve existing abilities in a wide range of domains, such as math, music, and sports.
When deciding what kind of material to interleave, you should use logical criteria given the reason that you want to interleave material in the first place, and make sure that the items that you interleave aren’t too similar or too different.
The effectiveness of interleaving varies based on factors such as the type of material involved and the environment in which the material is learned, so you should assess the situation when deciding whether and how to interleave; if possible, you should also assess the effectiveness of the interleaving over time, and experiment with different approaches to it.
Interleaving can be hard, and people sometimes underestimate its effectiveness; this is important to keep in mind both when it comes to interleaving in your own learning and when it comes to interleaving while teaching others.
In your specific situation, you might want to look into any overlap between your courses that could reinforce your retention and understanding of concepts. Perhaps discrete probability comes up in discrete mathematics (some courses/books include it). Certainly, permutations and combinations are likely to be covered in discrete mathematics; these topics are also used in probability. Integrals (calculus) may also come up when studying probability. Linearity from linear algebra also shows up in the linearity of operations of differentiation and integration. Vector spaces in linear algebra can have "vectors" that are sequences or functions. Matrices can arise in the graph theory part of discrete mathematics. More generally, standard proof techniques might be needed in both linear algebra and discrete mathematics.