Amber in a trich is no indication of anything than age of that specific trich... or a root problem if suddenly trichs start turning amber en masse. The trich has simply lived out its life span. Thats all.
As the trichs age new ones come along. The best indicator that a plant has finished is the swell. Buds have fairly steady growth rate through the weeks until they suddenly swell up. It is very noticable.
Once that happens the plant is basically "done." However, if the plant is healthy it will continue to live and buds will start growing again. New pistils and "foxtails", which are just new calyxs growing through the old ones. Sometimes stressful conditions will start fo tails early... because the plant is stressed and confused.
I one took an 8 week northernlights strain to 14 weeks waiting for 80% amber trichs. Just didnt happen....
Go by the swell. Once the flowers "explode" let the plant go another 10 to 14 days and then chop.
Also, the claim that more amber trichs = heavier high or couch lock is... well... mostly bs. I did an experiment. I harvested a few buds of a plant with only cloudy trichs and then later from the same plant harvested buds that were mostly amber trichs. Cured them all and then had some hardcores test them over several days... asking if they could tell the dif between the two. Thats a 50/50 shot. And guess what? The overall result was 50/50 wrong to right, which only indicated that my friends were just guessing.
Fact is the human body isnt sensitive enough to tell the difference in trich ripeness.
Although one friend did guess better than the others. He was about 75% ... and he confessed that he could taste the difference, which i believe because it makes sense. Just as we can all taste the dif in ripeness with fruits i suspect that such could be true of weed.
Anyway, watch for the swell in the caylxs in the buds. They tell the true story...