At the very least a backtest will make sure you are not trading a losing system. And God knows there are plenty of them!
Consideration: The system or methodology must allow for profit taking at designated levels according to the account performance statistics (this should not be confused with the RISK:REWARD ratio)
I am not young (55 year old) and luck has nothing to do with trading I can assure you that. But thanks anyway.
From my own experience and testing this seemingly sound approach usually degrades the performance of a system in most cases, sometimes severely.
life cant be packed in boxes (rules) , neither trading ... deal , with it and accept that and go from there... ie. extremes wether ups or downs it all comes back to its mean on normal circumstances... all u can do.. is narrow the range of that swings (emotional, psychological.. loss)... the weakest link in any tought out trading plan , is, and will always be.. you (the human) ... tryhards will overthink anything anytime but they wont find teh HolyGrail doing that.. because they wont accept or simply overlook the obvious.... get it ?