Great question. There is no 80/20-approved method of determining optimal pedaling cadence. In fact, nobody knows the best way to determine optimal pedaling cadence, or even whether such a thing truly exists. There is pretty strong evidence that what is considered optimal in a testing environment might not be optimal for experienced cyclists in race conditions. I think the best approach is to play around with cadence a bit, gather data (including perceptual data), tease out lessons, and apply them. All of this can, and I believe should, be done somewhat informally. To be too structured about it would be to pretend we know more about optimal cycling cadence than we really do, and could drain some of the fun out of your training.