B737 Undifferentiated or Other Model
Workload; Distraction; Communication Breakdown; Confusion
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Procedure; Chart Or Publication
During the arrival (STAR) to landing phase at SFO; we experienced numerous changes and non-normal phraseology/arrival instructions from ATC.  From XXX pushback through just prior to descent into SFO; the flight was uneventful.  Just prior to our Top of Descent; ATC cleared us to descend via; the SERFR 2 RVAV into SFO.  The clearance was then amended to descend via except maintain 10;000' MSL.  We were then transferred to NorCal and cleared to descend to 6000' MSL.  Additionally; we were given clearance for the TIPP TOE Visual to Runway 28L to cross MENLO at or above 4000' MSL.  I loaded this approach in the FMS and was prepared to fly it.At around 9000' MSL we received a call from NorCal that said we were departing Class B airspace and would re-enter in approximately one mile and given a new frequency to contact NorCal on the other side.  This seemed a non-standard phraseology and gave me pause; as if we were not following our assigned clearance.  Both Pilots confirmed; we were on the correct routing; airspeed and altitude/path.  Following check-in with the new NorCal frequency; our clearance was changed to an assigned heading and cleared for the ILS 28L; to cross HEMAN at or above 3100' MSL.After the ILS was intercepted; and we were on final; we were again instructed to side-step to Runway 28R for landing on that runway.  That approach and runway was loaded into the FMS by the Pilot Monitoring and the approach and landing was flown without incident.  After shutdown; both Pilots discussed the high number of changes and the non-standard Class B airspace call during arrival into SFO.  While all changes were handed well by both Pilots and we were able to stay ahead of the changes; there was the high potential for error/safety incident in the dynamic high traffic ATC/SFO environment.In the dynamic and high traffic volume SFO airport; ATC should refrain from multiple changes; if possible. All these changes challenged the Crew to stay ahead of the aircraft and maintain Situational Awareness.  During this arrival; it was a very high work load that was challenged by a nonstandard Class B airspace call and multiple changes.  While both Pilots successfully/expertly aviated through the challenges; it allowed the potential for errors and/or a safety hazard.']
B737-300 First Officer expressed concerns with TRACON's excessive clearance changes during arrival to SFO airport.