So I remember back then mods/admins/leads would allow you to leave and serve your slay a different time. So was this rule changed?
This has never been a set in stone rule. It's always been up to the staff member online to decide, and at one point it was even up to admin discretion. A mod may still allow you to do this, however it will always be up to their discretion. Just because one staff member allowed you to do it, doesnt mean another will.