Since I have a slow connection I thought cl_packetdup 2 might be good to prevent lags.
But today I found out that this setting has no benefits whatsoever.

Packetdup stands for packet duplication, it sends the packets twice (? not so sure )
When I turn it off cl_packetdup 0, I get a slightly better registration and the lags when they come (you cant really prevent them) are over much quicker.
So the ping might spike, but it lasts about half as long as with packetdup on and my game doesnt get interruptet.
Its like the game doesnt try to get these delayed packets.

Ok, so it has no use against lags.
The best thing comes now:
With my slow connection, I couldnt turn maxpackets to 100 without the ping rising.
Now with cl_packetdup 0, aparently less packets are sent so I can turn the maxpackets to 100 now.
This increases the bullet registration a lot.

My question is now:
What is packetdup good for?
It doesnt help people with slow connections/upstreams, it doesnt help against lags (makes them worse)
it sends more packets over your slow connection without making the registration any better.

Obviously people with fast connections dont need it either.

its more for a connection that has packet loss. if u have it set to 1 it sends the packet twice, once for the original one for the dup. im still not sure which works best for me