The grid is a contract. Break it once per page, and only when the content earns it.
The grid is not a constraint. It is a contract — between you, the reader, and the rhythm of the page. Every column you respect builds trust. Every gutter you honour gives the reader a foothold.
But contracts can be broken, once. A single oversized glyph that bleeds past the column. A photograph that ignores the margin. A pull-quote that hangs into the gutter. One break per page, deliberate, surprising, earned.
Two breaks, and the contract dissolves. The reader stops reading the page and starts reading the layout. Three, and you have decoration — which is what brutalism was a reaction against in the first place.