Fees are by default paid with the fiat money. This means that you bought
crypto for the specified amount (e.g. 25 USD) and the fees are charged
separately. When you want to spend 100 USD over 4 weeks, meaning 1 order
per week, the last order won't be placed since there is not enough fiat
money left.
In my case I wanted to spend 100 EUR a month, meaning 25 € once per
week. When testing it the first time I was charged 25,065 EUR. By
setting the fee to XBT instead of EUR, I can run the script 4 times a
month.