Seems many photographers rely on eye, camera settings or instinct when it comes to colour accuracy. So far as critical colour matching is concerned - it must be technical.
This even goes back to the days of film where all colour accuracy was performed post processing - one could not hope that the flash or natural light was exactly as the previous day. Sure if you were lucky enough to have a client who was not too fussy about it a simple "that will do" was music to your ears. Now we can almost guarantee accuracy pre-shoot with some of the tools available to us. My favourite is Colour Checker Passport, Simple effective and way more accurate that the camera.
Once you have a profile made up your are set, a simple eye dropper tool after that does the trick. Combined with Capture One (my personal choice) software there is no easier way to keep on the rails throughout the shoot. And it has to be said the colour correction is always off by at least 5%. For some clients this is too much - when you consider that theres a whole path of possible spoilers along the way from 'publish' to 'view'. Calibration of any laptop, PC or Tablet is rare in the business market, unless you are a designer, photographer or product developer you will not have gone to this much trouble. Nevertheless - it's fair to say what you publish to the web looks different to the end user.... mostly due to cheap screens and poor calibration.