I am not sure there is an industry that structurally requires less work. As Franco mentioned, there is instead a strong impact related to the Manager/Partner of the project in terms of work-life balance.
Normally long-term projects allow to have a better work-life balance though. The reason is, there are fewer strict deadlines from the client-side to satisfy. As a consequence:
- Due diligence projects are some of the worst exactly because they last few weeks only.
- Big transformation projects (for example in industrial goods or O&G) may last several months and may allow for better planning and fewer deadlines.
Having said that, I would not try to prioritize the sector where you should theoretically work less, but the one that you genuinely like the most. In the end, it is the one where you will feel the work is less demanding.
Also, remember that most people stay in consulting 2-3 years, and exits are usually correlated to the sectors you covered. Choosing a sector you enjoy can be thus the best strategy long-term.