Museum Leaders and We've Always Done It That Way

Don't let discussion end when the WADITW phrase is uttered. Ask the person to explain how and why the old way is still better. Keep talking.
If you want to depersonalize discussion, ask a staff member to play the devil's advocate at the start of the meeting, arguing the counter-intuitive position for the group.
Ask everyone to finish the phrase, "But what if we...." in relation to the project, program or event.
Build a post-mortem into all your events, programs and projects. Allow staff to evaluate while it's fresh in their minds, and lay out possible changes for the coming year---or scrap the whole thing.
Don't let this become a Millennial versus Boomer problem. Younger staff don't advocate change because they're young. They advocate change because they look at problems differently. That's what Boomers did in the '70's. Now it's someone else's turn.
Listen. Really, really listen especially to the folks who are on the front lines of whatever event you're evaluating. Strong organizations grow. They grow by adapting, and adaptation happens intentionally. Repetitive behavior stunts growth. That's not what your organization needs. Be the mold-breaker. Channel your inner Grace Murray Hopper and set the clock going the other way. Joan Baldwin