What I understand from @Popkon6 statement is that DCA help anyone wants to save BTC consistently according to the specified target. And this DCA strategy means that an investor will only make purchases every week or month with the same amount and does not care what the price as long as it has not reached the target. So, there is no influence on the impact of market downturn.
It is not necessary to invest with the same amount of money. It is okay to buy consistently every week or month in the DCA strategy, but there is no obligation for you to buy the same amount. You can increase the investment amount in any month/week if you want or reduce it if necessary. It completely depends on your ability. Investing in the DCA strategy means that you will invest continuously in any amount for a certain period of time depending on your ability and hold it for a long time.
In terms of the amount of money, if you have the ability to invest the same amount every week/month, then you can definitely invest without making any change in the amount. But if you have difficulty in maintaining the same amount of investment or you are unable to do so, then it is not necessary for you to maintain the investment amount. Invest as much as you can from the remaining money after meeting your daily needs. There is no problem in increasing or decreasing the amount of money as needed. However, I would advise you not to reduce your investment amount unnecessarily and not to invest more than you can afford. Invest in an amount that you feel comfortable with.