When you receive your salary monthly and you decide to remove the one for Bitcoin and then divide it so you can then be using it to invest weekly there's a high tendency that you may even use it for another thing with the hope of returning it which may never happen there by reducing your accumulation percentage for the month.
There is what they called discretionary fund, this is actually the funds that would be left after you must have done all your expenses and there are no more other things that will disturb you then you can use it for your accumulation of Bitcoin, so at this point I see no reason why you should use the funds you had budgeted on your DCA accumulation for another thing with the hope of returning it back because that shows that you are not discipline because an investors who have a goal to achieve on Bitcoin will enever allow anything to hamper there weekly accumulation.
I agree with you because there's such thing as emergency funds and then there's another called discretionary funds. An emergency fund is a cash cushion you build up for yourself to handle sudden life changes or demands that comes your way and it is very much advisable to build up your emergency funds to a reasonable extent before thinking of investing in Bitcoin so that your discretionary income isn't under any form of threat while your DCA accumulation is in progress.
No matter how you want and spread out your accumulation periods, any emergencies you've or concerns should be handled by your already set aside emergency funds and should have nothing to do with your discretionary income used for DCA accumulation.