This has been my experience as well. Something about the human brain just makes it very bad at observing a mocked-up screen layout and understanding how well i

This has been my experience as well. Something about the human brain just makes it very bad at observing a mocked-up screen layout and understanding how well it works in practice. Apply that to an entire application with multiple functions and the problem increases exponentially. Experience helps speed things up. But rapid iteration with a fast feedback loop is the best practice. Design is not doing the start of the loop, it’s doing the entire loop. Repeatedly.