Answering to this question is not easy and the answer could never be univocal: it all depends on the field you are working in and on the sensitivity of the person you are speaking to (the customer).
For example, if you are specialised in colours for cars or motorcycles, it is unlikely that you are asked to realise a colour that is different from the original one, unless our car has been exposed to the elements for a long time and this has significantly affected the colour.
On the other hand, if you own a paint shop that deals with coatings for walls or manufactured items in general (grilles, windows, lamps…), it is much more probable a customer with his favourite colour arrives at your counter. What should you do in this case?
As a good entrepreneur, you know well that realising a colour already coded by someone else is surely quicker and cheaper than taking the path of personalisation: uneasy journey with variable results.
As you know not all customers (probably including the lady in front of you) are ready to pay an extra cost to realise an ad hoc colour (personalised).
So, dig out of your archive the sample collection of already known colours (already developed and coded) and leaf through it to look for the colour you are asked, if possible, with the customer who wants to give you moral support by all means (after all, you are going to realise her dream in colour).
Unfortunately, not always this leads to the expected result: probably, after you examined all colour sample collections at your disposal and suggested some alternative colours, very similar to the one she wants but not exactly the same, you have to surrender to her insistence.
This is where LECHLER MAP comes into play, because even if we cannot replace your experience of colourists, we can help you to create an ARCHIVE OF PERSONAL FORMULAS: here you can memorize all colours that are not associated to a standard colour already coded and recover them easily later, if our lady comes back to the shop to ask for still half a litre of colour. All this based on one of our standard formulas or using your inspiration to realise a colour 'from nothing'.