You can clear night 6 without using cams at all, just listen for footsteps and have your mouse over left door to react to foxy running.
apparently the number of laughs indicates how soon Freddy is gonna attack, someone mentioned 5 and I kinda agree. Although on night 6 Freddie seems to attack at about 7 minutes 45 seconds, almost like clockwork in my experience, so close the doors at 7:40 until you hear the 5/6th laugh, whichever one she attacks on.
On night 6, Bonnie sits at the door for about 6 seconds after the third footstep and Chika about 5 seconds, if you refrain from flashing bonnie, you can use the jump scare noise to tell you if she's behind the door but for once per visit, if Chica or bonnie see you through the doors it seems the leave timer is reset, so spamming doors and lights, even if they don't sabotage them, will just waste power, you want them gone before you open the door at all. using optimal timing seems to drain 3-4% of power per visit
Foxy bashes on the door 3 times, each knock drains 2%, and the extra time wasted on the closed door drains an extra 1% for good measure, so a total of 6-7% drain per Foxy visit.
Each unit of power drain represents around about 10/11% per hour power drain. keep this in mind at all times, because if you can manage the power so you drain 16% per hour you can go the whole night without power loss. so theoretically you should be fine blocking foxy once per hour if no one else messes with you, or 2 Chicas/Bonnies per hour.
it takes about 8 minutes 40 seconds for a full night, about 1:25-1:27ish per hour, if you can make the power run out at about 8 minutes, and if you're lucky, Freddy will take her sweet time to nail you, this is if you're unlucky and the other three have been particularly aggressive. I screwed up three god runs not closing the door quick enough when RNG made them passive, where I could've easily completed the night without power loss, a bad hour is more than 2 Chica/Bonnie visits an hour/1 Foxy visit + any number of Chica/Bonnie visits an hour
the basic rule for "is this run power hungry or power conservative"
is if your power left is above or below a certain percent at the beginning of an hour.
12:00 - 1:00 83%
1:00 - 2:00 67%
2:00 - 3:00 50%
3:00 - 4:00 34%
4:00 - 5:00 17%
I'm working on night 7 420, I feel as if the period of time they wait at doors is drastically lower than night 6.