I had the same problem. How to show planks without showing places where's too much putty. Mostly in places with smal gaps I used wood dust mixed with wood glue, putty was only for large spots. You can use both there'll be no problem. My mistake was using putty for plastic models instead of wood type one.
First idea was using some acrylic paint. It would be ok and propably I'd finish, but because I was using brush there were overlaping spots which look really bad. So I scraped almost to 0 whole paint. I say almost because with my stupid luck paint soked in all dust+wood glue and putty places where I coudn't scrape it. Next I put chestnut stain and palisander stain.
So acrylic paint will be ok if you use airbrush or a sponge. Unless you can do it just with brush. Anyway good luck
This is the worst spot on my model
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