Poor, poor me, missing Tuesday's blog post because...I thought it was Monday. I had Monday off this week as I'm working this Saturday, so I got confused, while part of me still thinks today is Tuesday. In some alternate universe where time is 24 hours behind us, it still is Tuesday, so that counts...sort of.
Anyway, talking about deadlines, how important are they to a writer? It depends.
'Depends on what?' I hear you ask. How famous you are and how much of an unreturnable advance they've given you, both of which are linked. If you are very famous and you're book is likely to sell in the 100,000s, then you will get a lot of leeway with deadlines. If you're just starting out, or writing for a magazine, then deadlines are IM-POR-TANT: VE-RY IM-POR-TANT. I cannot stress how important they are.
A well-established author/writer/contributor who has a large following can afford to delay a book to perfect it...or take the Douglas Adams approach and listen to the whooshing sound the deadline makes as it goes past. Sometimes this helps with marketing by increasing speculation and desire for the book/article/whatever.
For an unknown author, it could prove the deathknell of a career as you get the reputation of being lazy and as a person not au fait with the publishing business. If you're signed with a small publishing house, then it may cost them a lot of money to have anything delayed and it won't do your reputation with an agent any good either.
Not only that, but agents and publishers talk to each other and pass around the names of the unreliable so they can avoid them.
So keep to your deadlines, and learn from my bad example.