>>2938109
as this anon says, don't use pieces with flaws in them in your board in the first place. i have always used a bit of glue to fill small gaps in my board glue ups. mind you these are pretty small gaps. anything that's big, i'd cut out. i also use mineral oil for for finishing.
my first board used fairly wide pieces, i would avoid if possible as they tend to bow more than smaller pieces under use.