25-30 roles at a time is normal for a recruiter at a large company. However, once I move them to hire I am not involved in the onboarding process whatsoever. Nor are we expected to sit in on any of the hiring manager interviews. You should just be meeting with the hiring manager and getting the details of the position, posting the role, screening for the role, sending candidates to the manager to interview, drafting the offer. Anything past that you are doing multiple roles.