In SH3 Commander the line "When in 3d views" is the setting that controls at what maximum tc level the crew still experiences fatigue. But you can set the other situations to a higher level if you wish. Then you can still TC at a higher rate, but not experience fatigue. The others are self explanatory I think. I advise critical events to set tc to 1. Just remind yourself that with high TC levels other units move greater strechtes through the world with less checks whether they are in range. So you could experience less contact reports or aircover. Which to some is a good thing, unless you get bored eaisly.