When it's a 50
When it's NOT a 50
Repeating a Gate
There is no penalty for repeating a gate.
In this diagram the paddler does Gate 1 three times, then does Gate 2, and then goes through Gate 1 again. There's no penalty.
You can do a gate as many times as you like, as long as it's in the right direction - but the gate is "live" until you start negotiation of the following gate, and any touch, on any pass, will count.
Once your head enters Gate 2, or you touch it, Gate 1 is "dead" and going through it - even in the wrong direction, or even touching it - isn't a penalty.
If, after doing Gate 2, the paddler goes through Gate 1 in the wrong direction, and/or with a touch, there is no penalty because the gate is "dead".