I agree. If there records of water parameters and the like, then the potential exists to come up with ideas that might help a person in the future. Without records, there is really little that can be learned... still fun to do.
Breeders will tell you that with tosai they have a difficult time predicting the future. After the Fall harvest perhaps 400 tosai will be selected for potentially growing another year ... in a pond that will get only 150. By Spring, the breeder can tell that the Hi is not as good as thought on 100 of them. Something else shows on 50 more. The breeder would be very happy to have 200 "worthy ones" from which to select the 150. The 50 "almosts" are the ones the hobbyist would like to get.

...If the experienced eye of the breeder has such a challenge, we lesser mortals have little chance.