Lagrangian points in formation of proto-Jovians?

Work by Canup et al, among others, implicates Lagrangian points in
the Giant Impact Hypothesis for the formation of the moon from a Mars
sized impactor which would have formed in the L4 or L5 points of the
sun-earth system. The general idea is that chaotic motion effects
would
have eventually allowed a large Trojan point body to wander near to
the young earth, ending in an impact. This raises a question...

There is some mystery about the very short time span for the formation
of our jovian planets, something like 2 to 3 million years, give or
take
a week :-) .

So:
Would the existence of early Lagrangian points in the proto-jovian
orbits
have measurably increased the efficiency and rate of mass accretion
of our four jovian planets? One might even envision extra Lagrange
points further along the orbits of the proto-jupiter and saturn, not
just
at ~60 degrees but ~120 degrees from the orbital primaries. Eg: a big
mass at a proto-jovian L5 point might facilitate its own L5' point.
At any
rate, whatever the geometries of stability, if they could have
occurred,
could proto-jovian Lagrangian points have acted as extra conduits,
following the Canup scenario, and thus feeding the giants which now
seem to have grown to full size in such a short time? Just a thought.