ISTJs can be very thorough and detailed in situations that I just do not want to expend all of the energy to do so.
When they build something, I know all the pieces will fit together and they will have all the materials at hand, and they will know the total and individual cost of everything, and they will have a schematic drawn out, and know the exact measurement of all the pieces, and...
... well, for things that matter, I can rest assured that if an ISTJ puts together a space shuttle or a car or an elevator or a house, it's going to fit together and everything will work as it is supposed to work according to plan.
[The only flaw usually for the ISTJ is not designing well enough in the sense of anticipating possibilities that might arise; but they will cover all the practical bases.]
ISTJs are loyal and faithful and firmly committed. They are very trustworthy, when they make a promise.
They also can handle intellectual criticism. If the criticism is impersonal and not buttressed by lots of statements that Feeler types often need to "soften things," they can swallow it easily and move on and even dish it right back.
They also give criticism. The mature/thoughtful ones can give a very impersonal, honest appraisal of something. And as long as the something is not a "person," the feedback is very exact and practical and realistic and truthful.
And... do I need to say that, if I need to balance my checkbook, I'd rather let an ISTJ do it?
