The most common mistake in digital product development is to view the design as a 'layer to beautify later' and set up the budget accordingly.
Whereas the data is clear: users judge an application in the first 30 seconds, and the vast majority of users with poor experience do not return. The budget allocated to the design is insurance to ensure that your acquisition costs are not wasted.
A correctly constructed design process also reduces the cost of development: tested prototypes prevent the software team from developing the wrong thing from the start.
