For a well defined EA where the requester has taken the time to define three items.
1. The conditions fo entry
2. The conditions to manage an adverse trade.
3. The conditions to manage an positive trade.
I find that I can nearly always do the initial version, confirm it with some backtesting and a small amount of forward testing for my minimum EA development charge of $40US.
You will note that I use the word 'manage' to describe the conditions with the trade on. I encourage my customers to think how the EA can be used to make 'mid course corrections' to their trade rather than simply holding on with the static stops and takeprofit levels. Conditions change and so should the trade. I expect that in my basic effort level.
Jim