You need very little recovery time between keystrokes to cool and lubricate the flexor tendons. If you type constantly, however, the need for recovery builds. It takes longer to recover from these motions. Many studies recommend a 10-15 minute break each hour to give yourself the recovery time you need. This needn't be a break from productive activities just a break from your keyboard.
Exercises can help, too.
Repeat several times. With arms outstretched in front of you, raise and lower your hands several times. Variety is the key. CTS occurs most frequently in workers whose motions are not only repetitious but are kept up for hours at a time. If you use a keyboard, structure your workdays to include a mix of activities each hour.