Everyone who has ever traded for more than a couple of hours have had episodes where their trades are wrecked because of bitcoin volatility reflecting on the whole market.
What tips do you guys have regarding protecting yourself from bitcoin sudden moves?
One of the ways to protect yourself is to have money on both ends, if your pair is btc/stable coin (or any other pair) you need to have amount of bitcoins and stable coins. When price change directions simply add more money to your position, for example you buy and price drop, what you do is to buy again, and if it drops more buy again and hold your positions, bitcoin always bounce back, sooner or later. It's ok to try to short sometimes, when you think that price will go deeper sell all and wait for price to go to bottom and buy then, it's tricky to do it, sometimes you can lose money if you choose wrong moment.
Trading is tricky and risky, some sudden moves can be a terrible for your open orders, but sudden moves are the ones that can make you money if you risk and trade like you expect them.
As you say trading is not an exact science and depending on who you are as a trader you can chose different strategies, the strategy that you describe can be very effective but only if you have a lot of capital to spare to keep averaging down the price at which you bought your coins and if you have the patience to hold your coins.
And very few people in the market have the skill or the natural characteristics to pull off something like that, I know that I could not, and it is the reason I sell my coins once I have decided that the position has moved too much against me.