Is there a correlation at all or is everybody different?

For example, I am on 1200mg of lithium daily. My recent blood text just came back and my blood levels are only .6

I've read places that 1500 is the most a person can take. But is the blood level more important? Could someone take 10,000mg a day if their blood level was in range?

And vice versa...does my stability have to do with my blood level? I feel stable, but my blood level is on the lowest end of the spectrum for therapeutic levels. Are some people stable with lower blood levels, even below therapeutic levels?