I will answer the second part of that question first.
Lets use the apple logo as an example. It is simple and iconic. What would you think if you saw the Apple icon somewhere without the signature bite-mark? I would imagine that you would think, “This is obviously some cheap knock-off!”, and that probably wouldn’t be far off the mark.
Apple have been so consistent with their Apple icon, that they have taken something as common as an apple, applied a bite-mark to it, and have managed to make that entirely their own. If you did a google image search for ‘apple’, you would be lucky if an actual real apple popped up on the first page. Even the original fruit doesn’t feature anymore. Now that is good branding, and its secret? Consistency. With this example, I hope I have made the relevance of design consistency obvious.
On to the first part of the question,
So how do companies like Apple achieve this consistency? It really is all about designing the right icon or logo up front, and putting together a set of rules that you stick by no matter what.
If the icon is on a black background, it will be silver. If it is on a white background it will be black. It will always have a five-centimetre border all around. It will never be stretched out of proportion. Always maintain hierarchy… etc. you get the general idea. Its about making up the rules that are relevant to your design, and sticking to them to the bitter end.
This consistency is not something that can be achieved overnight. You have to build consistency into your brand. There are a lot of things that can be catered for up front, but you are always going to find challenges applying your brand to something that just wont let you apply the rules. In this case, that application becomes an exception and an addition to the rulebook. Whenever your brand is applied in that kind of situation, you can make sure that you follow the same procedure that you did the first time.
A nice exercise is to take out your business card, letterhead, comp-slips and anything else you can find with your logo on it, put them down on a desk alongside each other, and ask yourself a couple of questions,
Do they all have the same logo?
Are the colours the same?
Are all of them proportionately in the same area?
You will begin to notice very quickly whether or not your brand is consistent or not.
Let me know your thoughts.