I agree, our memories are not perfect so if we do not keep a trading journal eventually we may forget about the reasons why we made a trade in particular, and how can we improve as traders if we cannot look at our past trades an evaluate them with our new skills and experience? This is where a trading journal shows its true value, as if you keep detailed records of every single trade you made, and even what you thought at the time, you will be able to understand what you did right and what you did wrong, and this will accelerate the rate at which you learn and improve your skills.
The journal also serves as material for evaluation when the trade is complete.
From the evaluation, you will find what is wrong and what must be corrected.
The trading journal will also be useful to support trade management to be more well organized and the strategies applied are in accordance with the journal that has been created.
It's not too difficult to keep a journal, in fact I can also create it in Microsoft Excel and record some trades made every time an order is completed.