Rune Factory - Monster task help - only 1 monster per task ???

Is it true that you can only have 1 monster working at 1 task ?I had 3 monsters - 2 mama and 1 tundr and i set all 3 of them to watering but only the tundr did the watering the other 2 just slacks off at the hut ?!

Yes only one at a time can water. eg the first monster will come out and water then go back to the hut, then the secon monster will come out and do some watering etc.

thanks much.