Fair enough, could you share the settings used.
I assume you see a green tick in game by the HQ Texture pack?
I mention as i see videos on YT of people claiming to use the HQ Texture pack but don't actually have it installed despite being able to select Ultra Textures form the menu.
The tricky part is being able to discover at what point utilisation degrades the experience. And that's the difficult part to test and monitor.
Some people can't detect minor hitches, stuttering, some people won't notice if the game is lowering texture quality so as to not degrade the performance.
It's pretty difficult to test and monitor this it seems. I guess we could monitor 0.1% lows, but monitoring the game changing the Texture quality on the fly is probably hard to detect unless its blatantly obvious.
I never realised until recently that games have started doing this. As if the anyone though the waters could get even muddier, but here we are.