Transits to angles

How would you interpret many slow-moving transits to chart angles (AC/DC and IC/MC) happening simultaneously? Does this occur often?

For example, in 1999 - 2001 I had Pluto conjunct DC, Uranus conjunct MC, Saturn conjunct AC and Jupiter briefly joined Saturn in 2000.

An angle is the doorway to a new quadrant. So these heavy transits usually touch off a 'trend' rather than an event. A lot depends upon the character of the planets in that quadrant and the aspects made around the same time as these heavy planets enter the quadrant.
When planets are square in space, as Uranus and Pluto are right now, chances are there will be people who have these on angles.
So it's really not that rare. Some people have them by birth!
think of the children born during that time you noted....they will have that their whole lives.
LIN