Remember that unexpected things can always happen. On one occasion, a linguist agreed to perform a request of mine for free. The translation seemed to be easy and nothing foreshadowed any trouble. Having assigned the project I went to a meeting with peace of mind. When I returned, I discovered that nothing went according to plan. First, the linguist had problems downloading the file. When they did manage to download it, it did not open. Finally, the linguist realized that they needed more context to deliver a quality translation and had to perform extensive research. As a result, much more time than estimated was spent on this "easy" translation. Of course, I thought it would be right to pay the linguist for the work.