Dont think so. It seems to me that SMB47B (And 46D perhaps) has
got their fixed shift. Always seen on the same shift for the past
few weeks. The order of buses for 851 has also changed
SMB47B was seen with SMB93S back to back some times already.
Suspected to be between the shift of SMB93S and SMB76S
SMB175P did cameo on that particular shift, which increased my
suspicion that SMB47B does have a fixed shift.
For SMB46D I'm not really sure for now (though I guess it's
closely related to SMB73A