Depends on the goal, sometime if I want to try and encourage genes which express themselves at a higher level when the temps are cold, anthocyanin the pigment is largely from exposure to cold. When we talk about trichomes you have to understand what is good for rapid growth and optimal for photosynthesis is not optimal for preservation of the trichomes.
My personal entire premise is to go as hard as possible in the first 4-5 weeks of flower, and as soon as trichome production ramps up my entire priorities change to trichome preservation.
Ideally you want to keep a 10 degree swing between day and night to prevent undue stress, but if I'm going for anthocyanin I can drop it by 30F overnight.
The lower you drop your temps though the less cellular respiration will drastically drop and the entire process is temperature driven.
Reduce the oxidative workload on the plant's, reduce dli, reduce temps, open up the oxidative workload so she can produce the antoxidants she needs like thc.
Light and heat accelerate the decay of thc to cbn. Your job is to slow thay motherfucking process down as much as possible while still give her enough juice to grow and actually fill the trichomes rather than just bake them to fuxk until you get 10% amber 30% milky and 60% clear glass. "My trichomes are ready", sure they are buddy.