Yes mate the time keeping is very important ! you have to work out how many laps you do on fuel (Our r1's do 55 mins on 24L) the time keepers have to write down every lap time, real race time, calculate ETA next lap and time pitstops as they are all very important. You are also the first point of contact for the rider and if you don't bring him in at the right time the rider will not be happy with ya as they have just had to push it in as they ran out of juice.
I was doing 2 hour stints at le Mans on time keeping and once you get the hang of it it quite easy.