Saying what you mean will keep you out of trouble. Users appreciate when you say what you mean because it keeps them on track and out of trouble. Inaccurate and/or imprecise words are bound to mislead at least some users. If you say, “The product will be delivered in 3 days,” but by that you mean that it will be delivered in 3 business days and are not counting Saturday and Sunday as days, then you are going to hear about it from your customers. If you say that the product will be delivered in 3 days, then the product should be delivered in 3 days.
In the words of Robert Louis Stevenson, “Don't write merely to be understood. Write so that you cannot possibly be misunderstood.”