Without question, both. A blended approach to a specified range of targeted profits per specified time frame. When you have taken the time to research, design, test, optimize and build the right set of decision support trading tools, then operating your trades using a blend of both becomes a lot more doable.
If you have not coded the EA, or if you have not designed the EA, or if you did not participate in the coding or design of the EA in some meaningful way, then you are playing Russian Roulette without knowing anything about Russian Roulette. So, you are playing a game without an understanding of the mechanisms behind the game itself. That's more than dangerous. That's the very definition of foolish.
Or, you can just trust everything to the EA Developer. However, when you do that, you've done nothing more than what an Investor does when capitalizing a Hedge Fund. At least with the Hedge Fund you get a Prospectus and a synopsis view of how the fund goes about managing its capital. When you turn it all over to the EA Developer and you know basically nothing about why or how the EA succeeds and/or fails, then you have just transitioned yourself from Active Proprietary Trader to Passive EA User. Such an individual might be better off going with a Hedge Fund. At least there you get some professional management, a prospectus and some insight into what the fund actually does with your capital.
I sometimes us an EA that someone else coded. However, I designed, wrote and edited the Specs to be coded. I know exactly what the EA does and can track its behavior to the letter of the Specs that I designed. I designed the trade logic and both indicator and signal logic that drives it. That only thing I did not do was code the MQL. That's because I'm a Trading Systems Designer and Trader, not a Software Developer. Two entirely different worlds and precious few people on earth can do both exceedingly well.
I've met a few good Traders and a number of good Developers, but I've yet to meet the individual who really stood out doing both to a high level of success.
