I've Always Wondered why we harvest the whole plant...and can just guess it is down to Convenience......
Top and end buds that get most light are more Mature than buds further down or closer to the main stem.
And also the Reluctance to Test a bud.....
...I've seen it on other sites...like a Badge of Dishonour to take a bud off...
But Hell....don't Bugger about....If you Wonder if your plant is ready...just take a Test bud off....and Try it.......
Tailor your Meds in....find the Optimum time on a cross for You.
Top Tip...if you are Desperate.....take the Sugar Leaves....leave the bud to mature....even the Sugars are stronger than bud I've bought.....