There are a number of scenarios where this is a great idea. I have done PSAT/SAT/ACT sessions with small groups (up to six students.). I generally don’t go larger than that because personal touch and individualized attention are compromised. I have been asked, however, to lead a half-day session, prepping a full class onsite at a school for standardized tests. That scenario can be adjusted to do an online “Zoom-like” presentation.
Many “prep companies” will do in person or online sessions with a classroom full of students. I am VERY wary of “jamming in as many kids as possible into a room.” “Lectures” have been proven to be less efficient and beneficial to students than other forms of “classroom learning.” Small groups and/or Socratic methods most often are more beneficial to the students.
When tutoring multiple students simultaneously in a given subject, the students need to be sufficiently close to each other in their level of mastery to make the session productive.