One of the things that I try to balance when writing out test scripts for manual testing is trusting that the person executing the test (which may not always be me) is reasonably competent to know how to do certain tasks versus assuming that the person executing the test needs instruction in how to do the task.
When working with a brand new application or brand new feature where I am involved in the design and requirements meetings, its easy to forget that there are assumptions and such made in those meetings that aren't always communicated across the board. At times, when I've had to hand off the test cases to someone else, usually I end up deeply involved in the testing due to this inside knowledge to the point where I feel like I should throw up my hands and take over the testing myself.
But if I'm too detailed in my test scripts, I find that I'm spending a LOT of time documenting the test steps and being rather nit-picky on those little details and end up getting behind in a project where I don't have as much time to test as I would like.
Is this a problem, then, with the amount of detail in the step-by-step descriptions of the test script or is this something that should be documented better in requirements and specifications? At what point does adding detail to a test script become a detriment to testing?