Design is rebellion, but with a spec
Breaking the grid only works if you know exactly where the grid was.
Every poster I love breaks a rule. Almost none of them break it by accident.
Know the rule first
Before you offset a headline by 40 pixels, you should be able to say what the baseline grid was and why you are leaving it.
Document the break
When I glitch a layout, I write down the seed. The chaos is reproducible, so a client can approve it and a developer can build it.
Controlled damage looks intentional. Uncontrolled damage looks like a mistake.