A bit of math
This math assumes nobody is using perks such as DH, BT, or DS, no insta downs, and nobody is healing ever.
The absolute minimum hits to get a 3 hook on all 4 survivors is 16.
2 for first down, 1 for each after that=4 hits per survivor*4 survivors=16
Now let's say that the killer has an absolutely perfect game. They are either chasing, searching, or hooking a survivor at all times. Here are some unrealistically low times that God killers don't achieve.
Searching- 5 seconds after hooking, the killer then enters a chase
Chasing- 10 seconds between every hit
Hooking- 5 seconds. After the killer downs someone, they have them on a hook within 5 seconds.
This does not take into account hooking or pickup animations.
16hits*10s per hit= 160 seconds
4 survs*3hooks*5seconds to put on hook= 60 seconds
4 survs*3 hooks*5 second search after each hook= 60 seconds
Total: 280 seconds.
If the killer plays a perfect game, and nobody heals ever, nobody dead hards, bt, or DS. The minimum time to get a 4k (which I know. Is too much. But. We are running a PERFECT killer scenario here. Hardest survivor game ever. Rank 1 madness) minimum is 280 seconds. Which is 4.66 minutes.
Of course this assumes no insta-downs and no slugging on the killer side.
If one person was on a gen at all times and 1 gen is 80 seconds. That is still 3.5 gens worth of time.
Even if the killer got an instadown EVERY TIME. And no other times changed to take into account stalking, etc... It would cut the total chase time from 120 to 80 seconds. (4 survs*3 hits=12*10 sec Chase) which makes the total time 240 instead of 280. Which is 4 minutes exactly. Which is 3 gens exactly.
Now that the math is done for a killer who instadowns every 15 seconds let's see a bit more.
Survivor. Take Kindred, Unbreakable, DS, Adrenaline.
This way you can ensure one person is always on a gen to guarantee your 3 gens minimum. Unbreakable to help counter potential slugging. IF you manage to have more than one person on a gen at a time, which I hope you do have at least two... Then you get Adrenaline to ensure you have unhooking capabilities. 99% the gate because there is no counter or punishment for doing so, use that hefty new health state to unhook your buddes at the endgame, and DS to ensure that you can get out the gate after being unhooked.
Things we didn't keep in mind: killer perks, slugging (we touched it), healing, medkits, toolboxes, or any of those stuns/health states from the above listed perks.
I'm not saying anything about balance here. I'm just giving you the numbers for a 15second killer and 1 survivor doing a gen at all times. It's 3.5 gens.
How to? Get survivors to read this post, run the build I said, and execute it.
You will get 3.5 gens every game minimum (calculated based on no survivor perks or healing or items)
You will win the rest. Especially if you take the perks and a toolbox and if the killer isn't a 15 second killer.
:D