You’ve got to be honest with yourself when you write a script.
Take out a stopwatch. Don’t rush your read. Allow for breathing room. Fix what’s not working. (That doesn't mean read it a little bit faster.)
If you don’t time your script honestly...- You will have to ask the talent to read faster than he or she should.
- You will end up doing multiple takes, hoping by some miracle the read comes in under time.
- You will get a poorer performance from the talent.
- You will end up having to scramble to figure out which words and phrases to cut from the script.
- You will risk having to explain to the client why certain words or phrases had to be cut.
- You will look unprofessional in front of your creative director, your producer, the engineer, and the talent.
- You will realize what’s not working and have plenty of time to fix it.
- You will have an easier recording session.
- You will have a better script.
It's really hard to kill a line you love to make the script time out right. But it's better to kill it early and have time to top it or work it in some other way than to have to do it under pressure in the recording studio.