The "gutter" is actually a WIREWAY. Article 376 will determine what flies, and what doesn't.
376.23 Insulated Conductors. Insulated conductors installed
in a metallic wireway shall comply with 376.23(A)
and (B).
(A) Deflected Insulated Conductors. Where insulated
conductors are deflected within a metallic wireway, either
at the ends or where conduits, fittings, or other raceways or
cables enter or leave the metallic wireway, or where the
direction of the metallic wireway is deflected greater than
30 degrees, dimensions corresponding to one wire per terminal
in Table 312.6(A) shall apply.
(B) Metallic Wireways Used as Pull Boxes. Where insulated
conductors 4 AWG or larger are pulled through a wireway,
the distance between raceway and cable entries enclosing
the same conductor shall not be less than that required by
314.28(A)(1) for straight pulls and 314.28(A)(2) for angle
pulls. When transposing cable size into raceway size, the minimum
metric designator (trade size) raceway required for the
number and size of conductors in the cable shall be used.
(Which, BTW, is the same thing it says verbatim in the Article on Auxiliary Gutters)
