Zarrar,
Automated systems do not seek 100% accuracy. That's the point most people missed on several threads about this subject.
No trading should seek 100% accuracy, this is a myth and can not be achieved imo.
However, automated systems work and are used everyday.
You are right about the slippage. There are ways to limit it [using the right trading platform, data feed, time frame, etc]. But it is not possible to remove it. Worse, it is not possible to really remove all human intervention. The market can and will spike sometimes. I still remember the Feds rate cut while most were caught short.
Tell me about slippage !
Again, the goal of automated systems is often misunderstood. The goal is to help trading, not to replace traders [systems which works are often systems built specifically for a trader or a firm]. It is a kind of super assistant. And yes, sometimes it can do 90% of the work or more, and there will be these times when you choose to deactivate it, just as a human trader decides sometimes it is not worth to be beaten.
So no holygrail here. Newbies forget about buying the 'winning software system'. Forget about the easy road. Trading is tough, no software you can buy publicly will make it easy.
Learn about the market, practice, practice, practice, prepare a lot of money you gonna loose [your learning fee]. And one day, when you can make money on a constant base, then you will be ready to have an automated assistant or system. That's the paradox, it does not work the other way around !
vpiNeo