As I mature as a game designer I see myself acquire thicker skin when it comes to my ideas. When at times I would lock down parts of my design out of stubbornness, now I seemed to have more clarity when placing my ideas in a game, especially when they don't work.
I think this is essential when finding the sweet spot in games: knowing that an idea might not work and actually being okay with it.
I've learned this with deeper conviction while designing Pillars of Civilization. I would try and solve a problem, come up with a solution, sit down to playtest, feel myself slowly die while watching my game fail to a very simple "lets try this and see if something blows up" mechanical-break method, and then continue to find the nearest blunt object and smash my forehead across it.
But I realized that this a very unhealthy lifestyle.
What I learned is that we may come up with a solution and it may look FANTASTIC but when we put it to the test it will most likely fall apart. And if we're not careful, we run the risk of adding and adding and adding mechanics on top of a broken base! Stepping back and chipping away at the REAL problems in our games is crucial. No matter how far into the game we are, throwing away a "good" idea to stop a bad mechanic from bogging down the game will never lose its effectiveness.
Ideas are temporary. Ideas are easily malleable if we allow them to be.
Just some thoughts as I continue my journey and improve as a designer!