EGT's are monitored for the same reason that AFR is.
The leaner you run at the top end (more power), the higher the EGT's. On a Scoob, 900 degrees C is about as high as you want to go!
Also the car will run a LOT faster if you thrash the car with 700 degrees EGT rather than pootling around town 300-450 EGT) and then blasting off! It does make a difference, at least it does in my RA
Russell