These approaches are called ILS PRM
and are only done to 28L/R. PRM
stands for Precision Radar Monitored approach.
It works best to have two aircraft paired together that have similar approach speeds, ie 2 747s or a 747 and 777 or 747 and MD
-11. These aircraft all approach at between 145 and 155 knots. The other key is to have them spaced less than a mile from one another so that the wake does not have enough time to spread out into the approach path of the following airplane.
If say a 747 and a 733 were paired together, wake turbulence separation will become and issue. A 733 normally approaches in the 130-140 knot range. He will be too fast if he flies at 145-155 to keep up with the 747. If he flies his normal approach speed, the 747 can catch and pass him. If the 747 gets more than about a mile in front of him, the 747 wake will spread out into the 733s approach path. Wake moves back, slightly down, and spreads out as time progresses. If wind helps push the wake into the approach path of the 733, oops.
Neat approaches to see, but they do have their issues. If NORCAL approach keeps everyone separated and the correct airplanes together, this is a good set up. If not, it's a ticking time bomb.