Workouts - how do you evaluate them?

[Seven Furlongs]

I opened this thread to ask how others utilise workouts. I've read various opinions on workouts, such as: that on the West Coast workout information is more reliable, that there should be a ratio of workouts to rest days if a horse is coming off a lay-off, that a horse does not need to workout if it has raced in less than 21 days, and that 5 furlong workouts are indicators of good form.

Also, I've read that workout information can be somewhat suspect as the workout rider may weigh more than the jockey who will ride the horse, that trainer x may choose to work out a horse at a leisurely pace while trainer y chooses to work out a horse at a vigorous pace.

How do you try and disentangle workout information and make it somewhat meaningful?

Currently, I use the 21 day rule mentioned above, that a horse has to have a workout if it has not raced in over 21 days, to determine fitness and I guage the speed of previous workouts at the same distance to see what kind of form the horse is holding.