As a writer myself, my job has very often been to also write...

As a writer myself, my job has very often been to also write on the job. So you get the script and a vague idea of how the scene might work, and you then add funny words or change the script. I'm not the world's best writer or the world's best actor, but I can do that thing where I can fix - or ruin - fix-slash-ruin, add quirk, add value.