I'm not a professional photographer. But I have seen the assistants work with the pros. As far as I can tell photography like most other fields have assistants/apprentices which mature then "strike off on their own." Most of the good apprentices already know what the master wants and is trying to attempt anyway. Basically apprentices are "go fors". So to me the answer is a combination of all the above with the addition that a pro may not feel he/she needs a "go for". AND they want things to be dificult for someone else. Much like they way it was for them when they learned. It seems silly but I've seen it many times and I suppose I've done it a little. I believe human's feel that life is a struggle and that people shoul struggle in order to learn. Consider it "payin ones dues". Bsteph