Bull8042 is right about trying to limit exposure to bacteria and stuff, but I'm not sure if that is what you're asking.
While cooling you want to take care to avoid contamination, with tinfoil, lid whatever.
However, during transfer to primary you want lots of air, the yeast need it for reproduction.
You want air after the boil! Splash it like crazy then shake it like crazy for 40 seconds to get O2 to your yeast.
Or you could transfer quietly, and aerate with a pump and stone, or oxygen tank and a stone.
It appears to me that most aerate during the transfer to the primary.
Regards.