Okay, I've heard a lot about the professionals who perform the same act for years without changes. I just have one question.

HOW LONG DID IT TAKE THEM TO DEVELOP THAT ACT?

I have one, only one, routine that is at the level I would like my entire performance to be. For me, that means it has to be original (by my own definition, which I won't go into here), suited to my personality and performance style, and well-polished. This routine is a little over four minutes long and took nearly a year to perfect. At this rate, I'll be middle-aged by the time I've put together a 45-minute show. I'm hoping future routines will develop more quickly (I wasn't just creating a routine, I was learning HOW to create a routine), but I'd rather not die of starvation before I have a show I feel is truly performance-worthy.

I've done longer shows. They've even gone over relatively well. However, they're not up the the standards I have set for myself.

I'd be perfectly happy performing one really terrific show for the rest of my life, but at this rate I won't live to finish developing this show.

I have a little the same feeling as you, but I suppose the pace to create something can vary a lot. In what aspect do you think you have worked harder and improve yourself while developing you routine?

Heh! I bet the thought of a year for a four minute routine freaks out most magicians but that's the way to do it, honing, streamlining, polishing and perfecting...after all "the practicing of an art IS the art."
As you become more sure of what you want from a routine that time WILL shrink.
I have been perfecting an ambitious card routine for about 8 months and when I feel its ready I am going to take Eugene Burgers advice and rehearse it for another month before I perform it.
It is time consuming to do it properly, but making miracles isn't supposed to be easy. But I like the idea of a routine being a perfect little play that I have scripted and tweaked to the point where it is exactly what I want it to be and I get exactly the response I was looking for and people are aware that they are with a real, skilled entertainer and THEY HAVE A GOOD TIME!...and that makes it all worthwhile.