OGKevin sure, the limit is actually a daily limit, not a monthly limit. However, the limit does need to be high enough for these monthly payments to go through, depending on the day these payments are being deducted. If it's all on the same day, then you need to ensure that your limit is high enough for these payments to be accepted.
You are correct in that the MC payments are deducted from the assigned account, instead of a pre-determined account as it used to be with whitelisting. As mentioned previously, this is the current implementation of this feature, but it does not mean that this is final.