In general, if the class is primarily lecture based, the in-class experience concentrates on reviewing material available in the text or through instructor notes, and involves little student interaction during class, then more flexibility with excused absences may be reasonable.
However, attendance flexibility as an accommodation may not be reasonable in every class. Attendance could be critical/essential to the learning objectives for classes that heavily rely on in-class participation as a method of instruction, classes where student learning is created/assessed in the classroom through experiential or conversational means, project-based or group focused classes where students spend substantial class time working and learning together, lab classes where student participation is critical and the functional nature of the course depends on physical presence for essential learning, field education or field experience classes that require a specific number of hours of participation, practicum, or within an internship setting over an academic term and/or classes where the primary purpose of attendance is to receive ongoing professor and peer feedback to progress in academic work.
For such classes, less flexibility with excused absences may be warranted.