Can I produce good writing with serious time constraints?

A reprise from the early days of the Literary Ladies blog:

Dear Literary Ladies,
I always thought that one needed great swathes of time to get any writing done. Now I hear that some esteemed authors worked in short bursts and still produced an enormous amount of brilliant work. I want to hear from one of you. How did you do it, and what did you do with the rest of your time?

I work from two and a half to three hours a day. I don't hold myself to longer hours; if I did, I wouldn't gain by it. The only reason I write is because it interests me more than any other activity I've ever found. I like riding, going to operas and concerts, travel in the west; but on the whole writing interests me more than anything else. If I made a chore of it, my enthusiasm would die. I make it an adventure every day. I get more entertainment from it than any I could buy, except the privilege of hearing a few great musicians and singers. To listen to them interests me as much as a good morning's work.

For me, the morning is the best time to write. During the other hours of the day I attend to my housekeeping, take walks in Central Park, go to concerts, and see something of my friends. I try to keep myself fit, fresh: one has to be in as good form to write as to sing. When not working, I shut work from my mind.

— Willa Cather, from a 1921 interview