Two issues here- is the time legally required, and is it useful experience. I have seen too many times where new pilots get a chance to ride right seat in a jet or a King Air, improperly log it as SIC, and then make the jump to thinking they know something about those aircraft. I recommend skipping the non-required SIC hours. Just make a note in your diary. By all means ride right seat in any aircraft you like however, it's great experience.