I had the great, inestimable, magnificent luxury of being able to take a sabbatical from work for four months at the end of last year. No emails, no meetings, no classes - just reading and writing. I accomplished a lot, but the thing I am most pleased about of all was that I was able to do a heck of a lot of just sitting and thinking about things carefully. It's easy to forget how unproductive you become if you are exposed to the constant drip-drip-drip of distractions that is the modern workplace. Doing anything really creatively good needs not just time but a certain type of time: your brain needs to get itself into a state that combines both relaxation with hard work.
You can hear a fascinating recent interview with David Gelemter on this topic if you are interested. The long and short of it is that our minds tend to switch between two modes of thinking - the rational, alert, analytical type ("up" thinking), and the mellow, sleepy, dreamy, intuitive type ("down" thinking). The reason why creating things is so difficult is that you need to combine both. You need to be able to let your mind wander in an uncontrolled free associative sort of way - that is, "down" thinking - because that's where inspiration comes from. "Up" thinking polices creativity too much through overanalysis. But at the same time you need to exert a certain rationality and analysis over the process to make things concrete and to judge what are the good ideas and the bad ones - and also to discipline yourself to producing the things that you are imagining. So to be productive - particularly productively creative - your brain needs to balance (or oscillate) between "up" and "down" modes.
You can't do this without extended periods of time so that you can find that balance/oscillation. Distractions break it.
I refer you back to my earlier post about the friendliness of boredom. If you want to create things, you need to get into a zone of stillness so you can think in a very special and careful way. As soon as you check your emails, your phone, or whatever, you get yanked out of that zone (it is almost a physical sensation) and you have to wait for a long time to get it back. Give in to distractions too often, and you never get into the zone at all.
One of the greatest challenges facing mankind today is distraction, and how it prevents proper thought.