I have no expertise on ironing, but I do on ironed shirts.
Dress shirts should be heavily starched, very white, and ironed to perfection. Over the years, I've found the little hole-in-the-wall Chinese laundries do a superb job.
You may remember Richard Gephardt, congressman from Missouri. I seldom agreed with his political views but I seriously admired his shirts: Crisp and ironed to to the ultimate limit. I bet he had ten of them in his office and changed them every hour.
If I could be impressed by a liberal Democrat, on any level, you have to assume whatever impressed me was outstanding. I really liked his shirts.