You raise an interesting point that has been recently studied. Surgeons at the Hand and Upper Extremity Department at Massachusetts General Hospital in Boston may be of interest to anyone with carpal tunnel syndrome. They took a look at type of work (desk versus manual labor) and its relation to return-to-work.
The patients in the study had a small open incision surgery under local anesthesia to release pressure on the median nerve (the usual cause of carpal tunnel syndrome). Desk workers were able to return-to-work sooner than manual laborers.
Forceful use of the hand in manual laborers was the likely reason nondesk workers experienced more time off from work and more work restrictions when they did return. This is probably the answer to your question.
In general, manual laborers can expect a slower time to return-to-work (up to one month minimum). They are advised to avoid activities that place force on the hand and wrist during wound healing. More work restrictions may also be recommended for the manual worker.
You might be interested to know that the study was also able to show that individual patient beliefs, expectations, and psychologic factors played an important part in return-to-work, too. Patients who expected to take no time off and get back to work right away did, indeed, take fewer days off and returned-to-work sooner than those who were anxious, fearful, and who expected a slow recovery time.
Younger patients who expected less time off were the first to return-to-work full-time and without restrictions. The conclusion of this was that early return-to-work after carpal tunnel surgery can be predicted by patient attitude and expectations.