Now that we have gone through 7 pages of discussion my concern has grown proportionally that I should have done Wilson right by giving more context to his observation. The gist; commands should be deliberate, non repetitive and clear.
Wilson Stephens from his book
Gundog Sense And Sensibility:
If messages are conveyed to a dog through two of its senses, one will cancel the other unless sufficient interval is left between them...
A retriever, sent for an unmarked bird, is short of its target area. The handler blows his whistle to attract the dog's attention, gives the accepted signal to the dog to extend the range, and calls 'Go back' or 'Get out',...These are all very proper things to do in such a situation, but are governed by the overriding stipulation, 'It's not what you do, it's the way that you do it'.
Contrast the techniques of an enthusiastic amateur and a seasoned professional in the case in question. Both obtain the dog's attention. But the amateur, heartened by this response, is over-quick to exploit it. His hand signals and voice command come concurrently. The dog then has messages coming in by ear and eye simultaneously. He makes what he can of a signal system which has now lost its clarity and absorbs only the general drift,...The professional is in no such hurry; he knows he will save time by using a little more of it. To him obtaining the dog's attention is nothing remarkable, but it is an asset he is determined not to squander. He therefore does nothing immediately but waits, with the dog's eyes on his face, while it's anticipation builds up, keeping it waiting and thereby increasing it's eagerness for the next order... Then, without haste but with painstaking deliberation, the handler pushes out his hand in one single action, sending the dog towards the game. He does not, at that stage, speak. If the dog shows signs of again hunting short of the target area he has the minatory 'Go back' available to keep him going, whereas the amateur had exploited it's first impact and could use this command only in repetition, inevitably with diminishing effect.
The professional had kept his commands sufficiently separate for the dog to assimilate them by ear, eye, ear successfully but without confusion...
The inference for us is that we do not increase the output of the canine mind by stepping up the input. More commands do not mean more action. The reverse is the case, because if orders are given more rapidly than they can be dealt with, the dog's concentration on those already given is broken...
To leave the maximum amount of clarity in the minds of dogs at work, the minimum necessary amount of commands and signals should be put into them...
There, that should clear up any mixed messages that I presented earlier.
By the way, pages 76 and 78 give the whole account.
Hang on! That's just what my GSP does.