I agree with most of the other experienced posters here; you need to document to the level of detail required by the rest of the testing staff.
There are a couple things to keep in mind with the quote, which came from a consultant. There are several things often done by consultants do to keep themselves necessary and in a billing status . (Please no cards and letters, I realize some take more responsibility than others). One is to not provide enough data for the client to carry on or repeat the work without them. Another is to make the client responsible for the quality of the consultant's job. In other words, the client tells me what to test, I don't use my experience to tell them what needs to be tested. That way, if something is missed or blows up in prod, it's the client's fault. There is also a basic flaw in the idea that repeatable tests don't find major problems - it assumes that every tester that analyzes the function won't come up with basically the same tests (as well they should if they're analyzing the same function). Totally bogus. This is duplication of effort and a waste of analysis time. It's redesigning the wheel repeatedly. Better to have it documented and add some time in the schedule for ad hoc testing, if that's even necessary. Good testers play around regardless of whether that time appears in the schedule.
When you are an FTE and you do the analysis on a given function, if you care about the future of your company and the mobility/future automation of your tests, you will document in sufficient detail that someone who has NOT analyzed the function can exercise/automate the test bank with little or no prep time. A consultant is usually not around long enough to see the fallout from failing to perform this step.
As far as documenting to the level of specifying action buttons, I think that's extreme, but have seen it done when tests have to be outsourced or turned over to user organizations to execute. If that is not the case in your company, I feel sure a happy medium can be achieved.
It's probably unlikely your fragments will make the cut, so you'll have to gird your loins...but maybe you can avoid the tedious and mind-numbing chore of documenting every keystroke .