My lessons in stock trading and from this forum...
1. Averaging down only works if you are a value investor. Even then we have to analyse the fundamental of the company carefully to see if it is earning profit to justify averaging down. If the company is suffering losses and the whole industry is suffering, then averaging down could be a very expensive lesson. I learned this the hard way. My losses from averaging down a few years ago were huge...well at least by my standard they were huge.
Some forumers say that averaging down only works for unit trusts where we are buying a basket of shares.
2. Averaging down is a big no no for traders. We cut loss at -10% or at whatever amount that we are comfortable with. I tried averaging down with Harta recently. I treated it as a hybrid investment (both trading and value investment). I suffered losses. Harta was like a bottomless pit. But having said that, averaging down worked with Top Glove, Supermax and Kossan at that time. Good return from there.
3. Cutting losses. This is painful but sometimes necessary. We refuse to cut loss even when we suffer 5 figure or 6 figure losses. Part of the reason is because we are in denial mode. Ego problem. How can our "superb" trading skills or investment skills be wrong??? Well, Mr. Market doesn't care. I have been there as well.
Capital preservation is paramount. Once your capital is gone, you are out of the game. Holding on to a blood red portfolio also denies you the opportunity to buy other better stocks. Better to lick your wounds and live to fight another day. A cliché I know.
I am just sharing my view. Please don't get offended whether you are currently holding banking stocks, glove stocks, penny stocks, etc which is suffering losses

It's the lost of opportunity while trying to avoid losses.