While it does take someone who's willing to push, learn, and create, changing espresso blends frequently is quite doable.
I roast all of our espresso on site, and I change our espresso about every 7-10 days, so I will do about 40-50 different espresso blends per year, and I never repeat. We always tell about our espresso -- name (something strange or interesting I concocted), beans, and basic tasting notes. Our customers have come to expect this.
This does two things: It allows me to educate through the cup about the vast array of flavors possible in coffee/espresso, and it gives me far more experience as a roaster. I did the single espresso blend thing for maybe the first year I was roasting, and it became boring because I wasn't learning anything new. I've been roasting over eight years now, and some several hundred espresso later, it's a hell of a lot more rewarding.
Salt Lake City, UT