Buying Bitcoin at any amount at different intervals without it being the same amount is also good but it is better to use the regular DCAing of same amount at different periods of time because it will enable the investor to be more active and effective in the DCA but for an investor doing irregular DCAing, they might not take it seriously since they feel they can buy at any time they want to but for someone DCA same amount, they are more disciplined and are more likely to get huge accumulations since they are always consistent in their DCA amount.
The reason why buying same amount at different periods doesn't really matter is that sometimes one may be having lot of challenges to do with money instead of not buying it is better to go for the amount that you can afford at the most important. The amount for DCA does not really matter , what matters is how often do you buy bitcoin.
So many give reasons why they find it difficult to buy bitcoin is because of too many challenges because they already have a specific amount of Bitcoin in their mind to buy, but it is not a must that one must buy that amount of Bitcoin they have in mind, you can also go for an affordable amount, it is better this way than postponing buying. No amount is too small to buy bitcoin as far as one is ready to always accumulate more Bitcoin from time to time.