Sometimes start date isn't the right stage of growth, if your plant was stunted in anyway they might have not matured as fast as the date. I start counting when i see hairs first pop. And also check your tryc for cloudy to yellow for maturity. If clear not done yet.
I don't ever have problem with my growth and my humidity is always around in the 30% range. I've lived in humid climates and not very humid climates. All the high humidity has every done for me is mold. Never seen any significant growth differences.
Higher experience level just means when you make mistakes that can possibly kill the plants. Ones that they say are for beginners can have issues and usually still make it through others just die.
Propably more than i need to but when things like timers fail or pumps fail, like they both have. If you don't check, things could become catostrophic in a very short period of time. Some setups never fail and some even with brand new equiptment still fail. Has me a little gun shy. So ya i sleep...
If the light from your phone wont cut it. Go to music store or somewhere you can get the colored film that goes on stage lights and get green. Tape it over your flashlight and you should be good to go. Still don't aim directly at plants.
At the end of your grow let your plants sit in total darkness for a couple days. They really bulk up. A friend of mine found this out by going to jail after he turned his lights off. Off for about 6 days. They got huge. It was not a drug related charge.
You might have shocked that one plant. It may take a long time to come out of it. If it is not growing larger at all start giving it water. I like to give only water a week and 1/2 to 2 weeks before i cut down.