After doing several projects, I noticed the following points about my work:

• I do the same amount of work in a 50 hour week as I do in a 60 hour week.
• If I'm motivated I can do a 50 hour week in 40 hours, and get out the door early to enjoy the sunshine and all is good.
• The quality of my work declines markedly after 50 hours, and it takes me longer to do even simple stuff.
• If I have an employer who is flexible, I'm happy to put the extra hours when it is required. If I get mucked about over time sheets I get annoyed and start to slack off.
• The good project managers that I have worked with have judged my performance by my output, not by bum on seat time.
• The more time I spend away from work, the more creative and lateral I am.

IT is a knowledge industry. It is very hard to measure the productivity of a coder. You have to rely on the motivation and the professionalism of the coder - and you therefore have to strenuously resist any initiative that may piss off that coder. Motivation is fragile, and very difficult to recapture.

What works for me is when my boss shows an active interest in my work, and gives positive feedback - 'the customers think this interface is really easy to use and intuitive', 'would this have been easier if it was done OOP?'. I really enjoy working hard when people appreciate my efforts (regardless of the £££s).

This has been a sample of 1 however so not statistically valid.