Is it permissible to give 57% of one's savings monthly as charity, such that only 43% remains of what might be subject to Zakat, and is it permissible to give all of one's savings as charity such that nothing remains that is subject to Zakat?

It is not obligatory to save money and accumulate the nisab (minimum amount) for the sake of zakat. Rather, zakat becomes obligatory if the nisab is reached and a full year has passed over it. The scholar Al-Uthaymeen clarified that accumulating money for zakat is not obligatory, because that by which an obligation is not completed is not itself obligatory. However, paying zakat becomes obligatory when a full year has passed over the nisab.