Show some respect
On Twitter today I found the most perfect illustration (courtesy of @amontalenti):
To me, this sums up why it’s not OK to assume you know someone else’s job. Nothing worse than being told “you just need to do this, it’s easy” by someone who has absolutely no idea what is required and has never done it, nor has any intention of learning the skill.
So, just don’t do it. And if you have found yourself doing it, find the recipient and apologise for treating them like an idiot. Next time, ask questions to understand the task, ask the specialist opinion of the person doing it, and work together to agree the best and quickest means to achieve the goal. Together.