The facts are that, while there are trichomes inside and outside the calyx structure, the largest concentration will exist on the outside. This makes sense when the surface area and volume on the inside/outside are taken into consideration. All things considered, verifying the flowers' maturity absolutely requires viewing samples of trichomes on the buds and making a determination of ratio of amber:milky. And each kola, and flowers on each cola, can mature at different rates, and each strain/grow has different genetics and different maturity rates. You can assess a plant's general maturity based on the flower times and outward appearance, but as to the quality and amount of THC - truly depends on the trichomes. And to get scientific about it and narrow it to percentages requires extensive testing.
Over complicating things is not very helpful for an inexperienced grower seeking guidance, they have enough to worry about.
Getting scientific about gardening is not the gardener's job, it's the scientist's job!
Nobody is ever going to that insanely thoroughly check, let alone lab test, every single flower on a plant numerous times, and then slowly harvest by disassembling it flower by flower, it's gardening not engineering.
If I should check every single plant I grow the way you suggest, I'd have to quit my day job and stop sleeping just to have time for that!
That's simply incorrect, the majority of trichs are on the inside unless the buds are extremely small and fluffy.
It's not possible to reliably assess anything by a spot check of 0.0000001% of the total populace. Especially not in the case of cannabis maturity, because the trichs on the outside show more amber than the trichs on the inside and trichs on leaves mature faster than trichs on calyxes, and lower flowers swell and ripen slower than top flowers.
Anyone with normal eyesight can tell overall amber levels with the naked eye (as an integral part of the overall assessment of the plant's status) it's a skill you have to learn but it's pretty easy to *know* how golden the shimmer has to be for it to be just right, and people have been doing this without microscopes for 1000's of years. Not much different from learning to pick out a ripe avocado, no electronic measuring instruments or number crunching needed.
You look at trichs for maturity not THC level or as you mention ''
quality'' which doesn't actually mean anything in this constellation, since it's a 100% subjective and unmeasurable parameter.
THC peaks in the milky trichs and begins to degrade, mostly to CBN, when they turn amber, so the scientific THC farmer chops too early forgetting about the 112 other known cannabinoids and their combined effect.
Desired maturity level is of course a subjective matter, modern commercial hash makers go for 0% amber, traditional commercial hash makers go for +50% amber.