Multiple reflective/insulation layers? [Small Grow;PC]

Multiple reflective/insulation layers?

Hi guys,

I'm just starting my 1st grow and currently ordering everything now, but i'm stuck with something. I've searched well about what reflective materials to use and have decided i am going to use maylar.
But the thing that i'm confused about is what difference would adding multiple layers do?
I've searched for an answer on Google and the forums but nothing has come up.

I've seen people have many reflective layers inside their grow such a with the use of maylar, bubble wrap and ali-foil.
The usaully put it in the order of, e.g

Case-> Ali-foil -> Bubble wrap -> Maylar -> their herb

Im wondering are the extra layers somewhat benefitial? , do they reflect more light? stop more heat escaping through the sides and just the fans?

Cheers for the answers if you guys know

the extra layers are for insulation....the mylar is the actual reflective part....i only use mylar....but if your grow room is having trouble keeping a steady temperature thats when i would use the other materials......people who have outdoor sheds,outdoor growrooms, etc.. would use the other materials.

Ahh man cheers that helped alot, my mind is now at rest .