Writing a spec script can take up as much time of a writer's schedule as he/she needs as it only matters when the script is complete. When a writer is working with a network, he/she is on a strict schedule. Writers are usually part of a writing team to ensure that the writing can be completed well and on time. The writing team may consist of anywhere between four to twenty (or more) writers. This all depends on the budget, show, and the preference of the showrunner. This may mean a room full of people sketching ideas and writing scripts, surrounded by pots of coffee to keep up their energy. What matters most in a writing team is that the work is done efficiently and well so that a show can air on time.