I'm currently working on a fairly old product that has been partially reworked 2 or 3 times by different teams. This has left the interface somewhat fragmented with different design patterns used in different modules of the application.

We have been asked to add a new screen to a module from a previous revision. Usually we would adopt the same pattern to keep the interface consistent, however this time we've discovered that using the same pattern is likely going to result in a poor and frustrating user experience.

We are having difficulties trying to agree on the approach we should take. Some agree that the pattern should just be followed to avoid confusing users. Others believe we should try and introduce different design to better suit the users task.

my questions:

• Should a consistent pattern always be used; even if it is detrimental to the end users experience?
• At what point does a poor experience make it acceptable to introduce a new pattern (approach?) for a single screen.