I agree that I said that cashing out 10% every time the BTC price doubles is a fairly conservative approach to price-based sustainable withdrawal.
Also, I am pretty sure that I said that selling 10% every time that the BTC price doubles is one of the possible portfolio management (and sustainable withdraw) methods that becomes available after reaching overaccumulation status. Guys will sometimes start to employ methods of selling BTC prior to their having had reached overaccumulation status, and to the extent that my opinion matters, I do not agree with selling BTC prior to reaching overaccumulation status unless you are engaging in spend and replace or you have some kind of an emergency or you are cashing out due to age and/or health concerns.
It is a very good sustainable withdrawal while almost giving good chance of buying back and having nearly same or even more amount of bitcoin later when price has pull backs, corrections, drawdowns or crashes.
When Bitcoin price doubles, your initial capital can be doubled too but it's very rough assumption because it depends on your entries and prices of accumulating bitcoin before.
If you have some kind of a spreadsheet program (such as Excel), it is pretty easy to keep track of your average cost per BTC at various points in time, and surely having a spreadsheet, there are all kinds of things that you can keep track of.
Surely, sometimes there could be confusion regarding some of your purchases and/or even your sales and/or other kinds of conduct that you engage in regarding building and/or maintaining your bitcoin holdings, yet you should still be able to come up with various average cost per BTC on various dates for your overall BTC holdings or even for BTC holdings that fall within smaller categories (perhaps based on dates acquired).
If DCA strategy was applied well, your average entry price would be not too far from a half of Bitcoin price (let's say its doubling price at a time of your taking profit action), so withdraw 10% of your investment capital is good.
With remaining bitcoin and capital, you can reaccumulate bitcoin in next dips without big decrease in your total bitcoin amount.
You are talking about trading. I have been specifically recommending against trading bitcoin. Bitcoin is amongst the best of assets and you want to fuck around trying to trade it?
One of the things about reaching overaccumulation status it can take 4-10 years or longer to get to such status that would then allow you to start to sell from your overaccumulated amounts, but if you are fucking around with trading, you might never reach overaccumulation status because you are too busy waiting or strategizing for BTC price dips that may well not end up happening... so you have way less likelihood of staying focused on bitcoin accumulation and getting to overaccumulation status which then would put you in a situation where you might start to employ price-based and./or time-based sustainable withdrawal strategies.
If you are fucking around with trading, you are likely just diluting yourself with the wrong focuses, including getting excited about small and meaningless levels fo profits and proclaiming that you are winning when you are not... but hey, whatever. Each of us is responsible for our own bitcoin portfolio building and management and we live with the consequences if we end up fucking up and not being able to turn back the clocks to fix our screw ups.