jonpinson
I think you will find bowling machines are there for the use of predictable bowling and as you stated to 'iron' out weak shots, not to play different strokes every shot. For less predictable bowling, have a net with people bowling as variations will be rife.
Unlike facing bowlers in the a net, the bowling machine is alot more difficult to face with variation of length and speed as there is not a bowlers arm to follow.
A bowling machine is not a toy and can be a dangerous thing and should be kept at a continuous length and speed.
Why argue a point I clearly made as if I said the opposite?
As I said, clearly, bowling machines can be used in a predictable and repeatable way which is great for practicing or perfecting a particular shot. Whether it be the short ball or a yorker, 90mph or slow spin. However if, as a batsmen, you only ever use a bowling machine to dismiss off stump half volleys through the covers, you will find yourself an awesome player of off stump half volleys, but you will be up the creek for anything else.
I'd much rather use a bowling machine in a more constructive way; for instance if I know that the opposition at the weekend have a particularly quick bowler who bowls back of a length, ten minutes of facing similar balls is beneficial. This can be difficult to replicate using real bowlers, as the rate of balls bowled is decreased. Not to mention, every team only has a certain number of decent bowlers. An entire net facing only pie chuckers is no good to man nor beast.
If you know what is coming, you can easily make yourself look like the best player in the world. There is no surprise, no guessing, and that is all well and good when making a youtube video.
Bowling machines in the wrong hands are indeed dangerous, and should never be used by anyone who doesn't know exactly what they are doing - of course. I'm afraid though that arguing that the deliveries should not be varied because it is unsafe to do so is rubbish. What do you do when you play in a match, politely ask the bowler to only bowl line and length?