Regarding colour, I believe there is no right or wrong way to brush paint the plastic ship's deck. For a start, no two will be identical. (even on the same ship)
Weather, human scrubbing etc. etc., all come in to play to affect shade differences.
Some folks can get bogged down in 'Technicalities' Keep it simple.
No two trees produce exactly the same shade of timber - Fact!
So Bob, if I were you I would free wheel, with no worries about 'Plank Counters'
I use Vallejo Air IJN. Ash Grey. Applied to the decks whilst they are still attached to the sprues. I use a wide flat headed brush and liberally apply the paint, then lay the stuff off in the direction of the deck planks. Then thin the paint a bit and apply a wet on wet, hit and miss. The thinned paint will be slightly lighter than the first coat.
No faffing about, straight forward, simple way and job done.
Don't get me started on those self adhesive veneer wooden decks! A good basis for the compost heap or to light our wood burner.
To each his own........It doesn't matter one jot how the end result is achieved. Be it long winded, super technical, or quick and easy, as long as the modeller is happy with the outcome, that is all that matters....even down to using stick on 'Wooden' decks.