Nourish and manage your career, not your job
I have been working close to full time since the beginning of this year for two customers. This is unusual for me since I have usually capped my work week at 32 hours maximum over the last 25 years. I have been enjoying the work and extra earnings but I believe that working too many hours carries a real cost and some risks:
It is far more important to manage our own careers than any particular job. You don't own your job but you do own your career. Just as you maintain your home and your car, careers require fairly much constant maintenance, including:
Life long learning of new technical skills.
Developing skills that enable people you deal with to also be successful: strive for win-win outcomes.
Networking that supports finding work, getting second opinions on important decisions, and leads on new interesting and useful technologies.
Time for self analysis: what has worked for you in your career (and life!), possible improvements, and understanding situations and attitudes to avoid in the future.
Individual jobs, including consulting gigs, are just tools for improving a career. While we owe employers our best effort, honesty, and transparency (e.g., share bad news earlier rather than later), we also owe it to ourselves to nourish and care for our own careers.