It depends on many factors. Though we can say,in general way, doing something in hurry can decrease quality and can be prone to errors also.
But when someone has acquired the efficiency and expertise by constant repetition and practice, most routine and stereotype tasks are not affected. On the contrary there are certain routine tasks which need speed and accuracy at the same time. Just take the example of Air Traffic Control. It needs sped, accuracy and extreme alertness and fast response. Such work need concentration and alertness. Mostly people for such jobs are selected by many falterings selection and evaluating their concentration, speed and accuracy.
In my own experience, I had experienced that I commit errors when the pace of work is slow and there is not multitasking. Actually the opposite holds for me.I am efficient when I have multi tasks at hand and do things fast.
Even in the case of posting for ISC,I have always experienced that my posts are good and winning prizes when I post them impromptu and fast. If I defer then mostly I end up not doing that. I always like to be busy with more than one task at hand. I feel more capable and efficient in such situations.