If you are 100% sure you have your electrolytes in check, more sodium doesnt help and you feel unwell in any way. That would make me stop anyway. And by unwell I mean no energy, brain fog, breathlessness, kidney pain, not keto flu symptoms.
I would say if you feel sick (and not just withdrawal from food), you should stop. I had to cut my fasts short when I was starting out especially cause I wasn’t aware yet of electrolyte levels & all which made me get dizzy & lethargic quickly.