I suppose in the ideal world you'd have someone you trust on every paddle and someone you trust in charge of the boat's movement.
Most bad things happen when the boat ends up over a cill, or snags something in the lock or gate. When that happens the most important thing is to get the water back to a safe level as quick as possible where it's possible to recover the situation.
In that situation, as the person responsible, you do need the others to react quickly to any instructions. Often that may be to shut the outlet paddles and open inlet paddles ASAP. Not easy if you are solo or only have help from a freind...and you have gates which are leaking!
As we found out on the Huddersfield Wide once, it's even trickier taking a 58ft boat through a 56ft lock with a very leaky gate. Be carefull folks.