Whats the VPD range/maximum that you use?

Doing some research Ive found multiple sources with varying "optimal" VPD ranges for each stage of growth. Ive heard from different sources that end of flower should not exceed:. 1.38, 1.48, 1.5, 1.6, and even 1.5-1.7

Im on my 3rd run now and it seems around start of late flower sometimes mid-flower when I ramp my VPD up to the 1.3-1.4+ range I start to get very minimal burnt and curled tips. I also sort of notice they are drinking much less and wonder if my stomata are closing on me. Would a lack of co2 cause the plants to be unable to handle a higher VPD? I feel like I was almost starting to see minimal overwatering so Ive cut back, starts around week 5 flower, and I know they will naturally start to drink a little less sometime around now or later depending on genetics.

Mine creeps up higher during the last weeks of flower as I drop the humidity to help prevent bud rot and PM. I drop my temps from around 82 down to 77 to compensate for the lower humidity and end up trying to stay under 1.6 VPD. If it gets higher for a brief period I'm fine with that but 1.6 is the ceiling I shoot for. It's a useful tool but I worry most about airflow and humidity during the ripening phase.