One of the 10 GDS Design Principles is to "Iterate. Then iterate again.", making small changes over time to gradually improve and shape a service.
The aim is to stop existing users from becoming disorientated by wholesale changes to a familiar design, and to ensure that workflow doesn't start to adopt the waterfall model (external link).
But the Apply to become an academy service needs wholesale changes to fix navigation and to move away from the non-digital design template it currently uses.
If you replace enough parts, it's a new thing...
The approach we decided on was to:
- design a revised and improved version of the service in full
- find sections of the new design that can be incorporated into the existing service with minimum disruption, and then implement them one at a time
- test each change thoroughly to make sure that we haven't made things worse
- continue moving pieces over until the whole service has been updated, or is close enough that the final 'push' will have minimum impact on existing users
We refer to this as 'slicing', and it allows us to iterate towards an end goal flexibly and without breaking agile design rules.
