A designer can do anything so long as it looks like it was done on purpose.
Information presented to a person who is not interested or ready to process it is effectively noise.
Remember, this is a cyclical process, so the team doesn’t have to agree on the perfect solution. You just need to figure out what to try next.
It’s less, ‘how do we communicate,’ and more, ‘how do we empathize?’
Any letter by itself is a mark out of context.
As long as it involves observing real people using your design, it’s usability testing.