Here's a small example of being attuned to my client:I remember a client coming into my office and as she sat down her body relaxed into the couch as if she had been holding on all day. She asked me, "This feels so good. Could I stay here all day"? "Absolutely, you can stay here all day", I said. "For as long as you want" I added.
Originally, the thumb, from the end to the first joint, became a unit of measurement, equivalent to about an inch. However, the “rule of thumb” has come to mean an estimate based upon experience, a rough calculation, as opposed to careful calculation. For me, it is a quick reference and/or an easy way to generalize from experience, particularly when in a discussion, when accuracy cannot be accomplished (no resources like calculator, reference works, etc.). You might call it, a mental “guesstimate,” or an estimate based upon experience rather than careful calculation.
Example: “About one fourth (25%) of a church’s attendance is children from 0 to 12 years old.” It is a starting point, it could be more or less, but it remains my rule of thumb.