I answered this in your other thread. The doctor is right. That is how I do it.
I thought the 4 hours was more for calcium and T4. Does calcium also bind to T3?
If not, then there is no concern over taking the T3 within 4 hours of calcium.
Typically people take the 2nd dose of T3 in the early afternoon, as it peaks in about 4 hours after taking it and then fads away over the next 4 to 8 or so hours. And if you take it too late, many people have a hard time getting to sleep.