Prof. Gleizer is possibly the nicest professor I've interacted with. From his overwhelmingly lenient grading policies (offering the option to redo exam problems in office hours for credit) to his emphasis on sound conceptual understanding, Oleg clearly cares about the wellbeing of his students.

During office hours, Prof. Gleizer's process for exam makeup was relatively straightforward. For any problems missed on an exam, Oleg would come up with a new problem grounded in the same conceptual area. If you could demonstrate learned understanding, he gave you points back on the corresponding exam problem. In order to balance allotted time for people wanting to redo missed exam problems vs people confused about the lecture topics, Prof. Gleizer made sure to take questions on lecture materials beforehand.

Go to this mans office hours! He literally will not leave until you understand what's going on in this class.

I went into this class not even knowing what a matrix was and left having mastered the material. Oleg is one of the most engaging professors I have ever had. His office hours are informative. Additionally he actually cares about your learning. When I took his class, he had a policy in place that allowed you to go to his office hours to make up missed points from the midterms. He would give you a new problem and if you could explain it to him step by step and were able to convey your knowledge, he would give you some points back. He did not believe that a single test grade should determine our understanding, that is why he allowed us to go in (on our own time) and show him that we knew the material.
Apart from this, his tests are by no means easy. They require complete understanding and at the end of every test, he gives an extra credit question which is usually theoretical.

MATH 33A with Professor Gleizer was a surprisingly enjoyable experience. At the start of the quarter, everything seemed rather overwhelming, as some of the problems were very time-consuming. Once I gained sufficient practice though--and the further into the quarter we got--I began to adapt to the situation and found the class becoming easier. Professor Gleizer really does try to emphasize the key concepts of linear algebra (such as the kernel, determinants, orthogonality, and eigenvalues) while also trying to make the class less stressful for his students.

With respect to the tests/exams of this course, I believe they were fair with respect to difficulty. The midterms were each five questions long, but he offered an extra credit proof-based question at the end of each, making it possible to score a maximum of 120/100 on each of the midterms. The final was ten questions (no extra credit) and we had a 24-hour period to take the exam because of the COVID-19 situation. Some questions were a bit calculation-intensive, but overall nothing too absurd for what we learned over the course of the quarter.

TL; DR: Professor Gleizer stresses about thinking in terms of questions, not answers, and helps students discover the answers to their questions on their own rather than directly giving the answer, enabling greater understanding. The tests in this class are manageable, with a decent amount of extra credit and aids to limit stress about the grading in the class.