Spreading industrial grade perforated aluminum over the top of the blown-in-insulation has been on my radar for a few years. It is primarily an upgrade for blocking summer heat radiating through the roof: mitigating about 97% of the radiant attic heat. In warmer climates the foil is attached to the rafters, and has little pinholes to allow convection to move the hot air up to the roof peak. The foil I used is made to be laid flat in hot/cold climates; it has larger punched perforations allowing moisture/condensation to pass through. Laying it atop the lofted insulation stops the cold air from pressing down and sinking through. Cold always drives downward, and the house heat meets the down-driving cold and creates a fast convection circuit that rips heat out of the house. With the diving force of the cold air blocked, the house should be cozier. Mostly though, it is for our triple-digit summers.
I pre-cut sections of foil out on the deck, then used a 10 foot run of pvc with a nail taped to an end to pierce the foil and push it into place. Before pushing it I added upright tabs of aluminum heat-tape, and after pushing it into place, used another pvc run with a T ending to press the tape down onto the adjoining section of foil cover. It went pretty well, but standing on a little board by the hole for the ladder in a slippery tyvec suit and finding physical leverage to make things go where they needed was a bit like doing yoga-for four hours.