Pre shading...

No you don't, why? If you are doing a 1/700 scale ships it's to small to matter. I just finished building 7 carriers for a museum display the only thing I shaded were the 1/72 scale aircraft in the display.  A ship is a ship.  Its a huge collection of various iron and armor plates, totally cluttered up with details like cranes, liferafts, doors hatches gun tubes and the like.

If you want to vary some of the shades of your base colors and work a little detail into the hull. Carrier decks at least in WWII were wooden decks painted over with flat blue paints,  Put the darkest color down first and then lighten the same color and work your way out.  Be sure to pollute the deck with  oil stains, crash marks and heavy wear and tear.  If your painting any guidelines on the deck suggest you use a colored pencil instead of paint.  It looks more like the paint was applied to seperate planks.  If you use paint it flows and fills in all the cracks.  Also, depending on the details of the deck there seem to be places for metal on the deck, tie downs and spacers. The areas will be small, again use a pencil or a colored pencil to get the effect you want.

Really want to be clever, mount a few aircraft on a very thin wire and have a few lauching off the bow, or flying by on either side.  drill a hole in the aircraft and anchor the wire into a hole in the ships hull. The smaller the wire the less visable it becomes.

Good luck with the project.

There is also the scale effect to consider. Ordinarily I do not worry about scale effect- except with ships.  The scale viewing distance is way too little to create much atmospheric effect on ordinarly aircraft, car, or armor subjects.  But ships, at 350 or 700 scale, represent hundreds of feet of viewing distance, so the atmosphere does have an effect.  These effects are two-fold- first a lightening of color, so we sometimes lighten the color of paint.  But more important for the subject of the post, there is a contrast reduction!  Thus, panel lines that would be visible at 20 or 30 feet tend to disappear at 200, or 2000 feet viewing distance.  Preshading these lines to increase contrast is likely to look weird.

Don's right, when you get down to 1/700, even the few panel lines on an aircraft can get to looking rather odd, rather fast. Heck, on my Big E build I thought I was going overboard by putting modex numbers on the individual aircraft, not to mention squadron codes and logos ...