I'm an individual contractor (out of the US) and work on a Time & Material basis. I do knowledge work. My "problem" is that I do things much faster than the average knowledge worker. For example, a 20-minute email would take me only ~4 minutes to compose and send. This results in my hours being very little compared to others doing the same tasks as mine, and therefore me getting a much smaller pay cheque (but more praise and clapping!). Should I add some extra hours per week? If so, and if this was ethical, how much (%) should I add per week? Please keep in mind that I provide my own laptop, Internet, and electricity.
PS: Please edit the title. I'm not a native English speaker, and couldn't come up with a better title. I will delete this sentence afterwards. Thanks!