John raises an interesting point regards drawings, written dimensions and actual measurements not matching. Having worked for many years in the building design industry I gave up trying to explain why it was important that things are drawn, written and measured correctly and to scale, thankfully CAD has removed many of the drawn (not to scale) errors.
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Creating drawings that are both accurate and correctly dimensioned has always been integral to draughtsmanship – whether manual or cad. The biggest difference is that it is easy to change something in CAD whereas with manual drawing it can be a very time intensive task to change drawn details and occasionally it was just the dimension that changed and should be noted NTS.

However it should also be noted that more predesign work was carried out prior to committing the information to a manual drawing because change was not a practical option, whereas today with Cad the design tends to evolve and drawings are changing all the time.

Anyway you should never actually scale from a paper copy of a drawing – either manual or cad.