ISO advisor is the one

Every school that is allowed by UCSIS to issue I-20 has at least one person that is USCIS certified and we call him/her/them ISO advisor. Whatever he/she/they say about your taking courses will be what USCIS's decision too. Schools may be different on this, because their ISO advisors have different view. So if your school ISO advisor (not your department advisor)says you can't take over 3. You can't. Or ISO will report to USCIS that you violate status from certain date and are now out-of-status, and this out-of-status record may show up on every computer in all USCIS posts, all US consulates located in every country.