Being effective in a competitive strategy means that:
• You are operating in a profitable market space
• You have achieved some measure of competitive advantage
• What you’re doing can’t easily be replicated – there is a measure of sustainability
• And you have a market position that resonates with people
However, even though you dominate on a single value attribute, you will always have to maintain a minimum acceptable level of performance in the other two.
Being the cheapest still requires some level of quality and customer attention.
The highest quality still has a maximum price the market will bear and a minimum amount of customer attention/flexibility/customization.
And customer intimacy still requires a reasonable corresponding price and level of innovation consistent with what is bring purchased.
Dominate in one, but ensure that the level of your performance in the other two areas are not forgotten. There will always be a bare minimum in all three dimensions of your unique selling proposition.