Cutting canola after 50% seed colour change will increase crop yields because side branches have longer to fill and average seed size for the whole plant is larger.
The following two tables summarize the yield boost for later cutting:
Shelling risk: Some of the earliest pods may shell out with later swathing, but improved size and maturity for seeds in later pods makes up for this. Early shelling may also be a bonus if pods are shelling because they’re diseased and contain peppery seed that won’t amount to anything. One approach is to start swathing when the first crop reaches 50% SCC, and then swath canola crops until shattering starts and leave the rest for straight combining.
How quick does canola dry down? Under warm to hot and windy conditions, moisture loss can be as high as 2-3% per day. Later in September, more typical dry down would be 1-1.5% per day. A rough guide is that a 10% increase in seed colour change occurs with about 5% moisture loss. So the period from 30% seed colour change to 50% seed colour change, for example, would need a 10% drop in moisture. This may take 10 days in cool weather and only 3 days in hot windy weather.