Defoliate or not?

Hello
I have some plants at week 4 bloom. I did a tour of leaf pruning prior to bloom phase, but now it’s got thick again. So should I defoliate at this stage? Or when is better time to do that?
Also there are a few plants (sativa strain) whose leaves are lookinga bit off and not so green compared to other leaves of different strain. I’m not sure if it’s the genetics of the strain or are they lacking certain nutrient? (Photo attached)
Thanks in advance everyone!

You should show a picture of your grow area if you asking if you should defoliate. I’m not sure about the lime green leaf, maybe someone else can help but they will need more info.